April 2022 - Linux-stable-mirror

[PATCH 6/9] bfq: Remove pointless bfq_init_rq() calls

by Jan Kara

We call bfq_init_rq() from request merging functions where requests we get should have already gone through bfq_init_rq() during insert and anyway we want to do anything only if the request is already tracked by BFQ. So replace calls to bfq_init_rq() with RQ_BFQQ() instead to simply skip requests untracked by BFQ. We move bfq_init_rq() call in bfq_insert_request() a bit earlier to cover request merging and thus can transfer FIFO position in case of a merge. CC: stable(a)vger.kernel.org Tested-by: "yukuai (C)" <yukuai3(a)huawei.com> Signed-off-by: Jan Kara <jack(a)suse.cz> --- block/bfq-iosched.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 19082e14f3c1..d7cf930b47bb 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -2497,8 +2497,6 @@ static int bfq_request_merge(struct request_queue *q, struct request **req, return ELEVATOR_NO_MERGE; } -static struct bfq_queue *bfq_init_rq(struct request *rq); - static void bfq_request_merged(struct request_queue *q, struct request *req, enum elv_merge type) { @@ -2507,7 +2505,7 @@ static void bfq_request_merged(struct request_queue *q, struct request *req, blk_rq_pos(req) < blk_rq_pos(container_of(rb_prev(&req->rb_node), struct request, rb_node))) { - struct bfq_queue *bfqq = bfq_init_rq(req); + struct bfq_queue *bfqq = RQ_BFQQ(req); struct bfq_data *bfqd; struct request *prev, *next_rq; @@ -2559,8 +2557,8 @@ static void bfq_request_merged(struct request_queue *q, struct request *req, static void bfq_requests_merged(struct request_queue *q, struct request *rq, struct request *next) { - struct bfq_queue *bfqq = bfq_init_rq(rq), - *next_bfqq = bfq_init_rq(next); + struct bfq_queue *bfqq = RQ_BFQQ(rq), + *next_bfqq = RQ_BFQQ(next); if (!bfqq) goto remove; @@ -6129,6 +6127,8 @@ static inline void bfq_update_insert_stats(struct request_queue *q, unsigned int cmd_flags) {} #endif /* CONFIG_BFQ_CGROUP_DEBUG */ +static struct bfq_queue *bfq_init_rq(struct request *rq); + static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, bool at_head) { @@ -6144,6 +6144,7 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, bfqg_stats_update_legacy_io(q, rq); #endif spin_lock_irq(&bfqd->lock); + bfqq = bfq_init_rq(rq); if (blk_mq_sched_try_insert_merge(q, rq, &free)) { spin_unlock_irq(&bfqd->lock); blk_mq_free_requests(&free); @@ -6152,7 +6153,6 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, trace_block_rq_insert(rq); - bfqq = bfq_init_rq(rq); if (!bfqq || at_head) { if (at_head) list_add(&rq->queuelist, &bfqd->dispatch); -- 2.34.1

2 years, 7 months

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[PATCH 5/9] bfq: Drop pointless unlock-lock pair

by Jan Kara

In bfq_insert_request() we unlock bfqd->lock only to call trace_block_rq_insert() and then lock bfqd->lock again. This is really pointless since tracing is disabled if we really care about performance and even if the tracepoint is enabled, it is a quick call. CC: stable(a)vger.kernel.org Tested-by: "yukuai (C)" <yukuai3(a)huawei.com> Signed-off-by: Jan Kara <jack(a)suse.cz> --- block/bfq-iosched.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 1fc4d4628fba..19082e14f3c1 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -6150,11 +6150,8 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, return; } - spin_unlock_irq(&bfqd->lock); - trace_block_rq_insert(rq); - spin_lock_irq(&bfqd->lock); bfqq = bfq_init_rq(rq); if (!bfqq || at_head) { if (at_head) -- 2.34.1

2 years, 7 months

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[PATCH 4/9] bfq: Update cgroup information before merging bio

by Jan Kara

When the process is migrated to a different cgroup (or in case of writeback just starts submitting bios associated with a different cgroup) bfq_merge_bio() can operate with stale cgroup information in bic. Thus the bio can be merged to a request from a different cgroup or it can result in merging of bfqqs for different cgroups or bfqqs of already dead cgroups and causing possible use-after-free issues. Fix the problem by updating cgroup information in bfq_merge_bio(). CC: stable(a)vger.kernel.org Fixes: e21b7a0b9887 ("block, bfq: add full hierarchical scheduling and cgroups support") Tested-by: "yukuai (C)" <yukuai3(a)huawei.com> Signed-off-by: Jan Kara <jack(a)suse.cz> --- block/bfq-iosched.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 89fe3f85eb3c..1fc4d4628fba 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -2457,10 +2457,17 @@ static bool bfq_bio_merge(struct request_queue *q, struct bio *bio, spin_lock_irq(&bfqd->lock); - if (bic) + if (bic) { + /* + * Make sure cgroup info is uptodate for current process before + * considering the merge. + */ + bfq_bic_update_cgroup(bic, bio); + bfqd->bio_bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf)); - else + } else { bfqd->bio_bfqq = NULL; + } bfqd->bio_bic = bic; ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free); -- 2.34.1

2 years, 7 months

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[PATCH 3/9] bfq: Split shared queues on move between cgroups

by Jan Kara

When bfqq is shared by multiple processes it can happen that one of the processes gets moved to a different cgroup (or just starts submitting IO for different cgroup). In case that happens we need to split the merged bfqq as otherwise we will have IO for multiple cgroups in one bfqq and we will just account IO time to wrong entities etc. Similarly if the bfqq is scheduled to merge with another bfqq but the merge didn't happen yet, cancel the merge as it need not be valid anymore. CC: stable(a)vger.kernel.org Fixes: e21b7a0b9887 ("block, bfq: add full hierarchical scheduling and cgroups support") Tested-by: "yukuai (C)" <yukuai3(a)huawei.com> Signed-off-by: Jan Kara <jack(a)suse.cz> --- block/bfq-cgroup.c | 36 +++++++++++++++++++++++++++++++++--- block/bfq-iosched.c | 2 +- block/bfq-iosched.h | 1 + 3 files changed, 35 insertions(+), 4 deletions(-) diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index 420eda2589c0..9352f3cc2377 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -743,9 +743,39 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, } if (sync_bfqq) { - entity = &sync_bfqq->entity; - if (entity->sched_data != &bfqg->sched_data) - bfq_bfqq_move(bfqd, sync_bfqq, bfqg); + if (!sync_bfqq->new_bfqq && !bfq_bfqq_coop(sync_bfqq)) { + /* We are the only user of this bfqq, just move it */ + if (sync_bfqq->entity.sched_data != &bfqg->sched_data) + bfq_bfqq_move(bfqd, sync_bfqq, bfqg); + } else { + struct bfq_queue *bfqq; + + /* + * The queue was merged to a different queue. Check + * that the merge chain still belongs to the same + * cgroup. + */ + for (bfqq = sync_bfqq; bfqq; bfqq = bfqq->new_bfqq) + if (bfqq->entity.sched_data != + &bfqg->sched_data) + break; + if (bfqq) { + /* + * Some queue changed cgroup so the merge is + * not valid anymore. We cannot easily just + * cancel the merge (by clearing new_bfqq) as + * there may be other processes using this + * queue and holding refs to all queues below + * sync_bfqq->new_bfqq. Similarly if the merge + * already happened, we need to detach from + * bfqq now so that we cannot merge bio to a + * request from the old cgroup. + */ + bfq_put_cooperator(sync_bfqq); + bfq_release_process_ref(bfqd, sync_bfqq); + bic_set_bfqq(bic, NULL, 1); + } + } } return bfqg; diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 7d00b21ebe5d..89fe3f85eb3c 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -5315,7 +5315,7 @@ static void bfq_put_stable_ref(struct bfq_queue *bfqq) bfq_put_queue(bfqq); } -static void bfq_put_cooperator(struct bfq_queue *bfqq) +void bfq_put_cooperator(struct bfq_queue *bfqq) { struct bfq_queue *__bfqq, *next; diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h index 3b83e3d1c2e5..a56763045d19 100644 --- a/block/bfq-iosched.h +++ b/block/bfq-iosched.h @@ -979,6 +979,7 @@ void bfq_weights_tree_remove(struct bfq_data *bfqd, void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq, bool compensate, enum bfqq_expiration reason); void bfq_put_queue(struct bfq_queue *bfqq); +void bfq_put_cooperator(struct bfq_queue *bfqq); void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); void bfq_release_process_ref(struct bfq_data *bfqd, struct bfq_queue *bfqq); void bfq_schedule_dispatch(struct bfq_data *bfqd); -- 2.34.1

2 years, 7 months

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[PATCH 2/9] bfq: Avoid merging queues with different parents

by Jan Kara

It can happen that the parent of a bfqq changes between the moment we decide two queues are worth to merge (and set bic->stable_merge_bfqq) and the moment bfq_setup_merge() is called. This can happen e.g. because the process submitted IO for a different cgroup and thus bfqq got reparented. It can even happen that the bfqq we are merging with has parent cgroup that is already offline and going to be destroyed in which case the merge can lead to use-after-free issues such as: BUG: KASAN: use-after-free in __bfq_deactivate_entity+0x9cb/0xa50 Read of size 8 at addr ffff88800693c0c0 by task runc:[2:INIT]/10544 CPU: 0 PID: 10544 Comm: runc:[2:INIT] Tainted: G E 5.15.2-0.g5fb85fd-default #1 openSUSE Tumbleweed (unreleased) f1f3b891c72369aebecd2e43e4641a6358867c70 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014 Call Trace: <IRQ> dump_stack_lvl+0x46/0x5a print_address_description.constprop.0+0x1f/0x140 ? __bfq_deactivate_entity+0x9cb/0xa50 kasan_report.cold+0x7f/0x11b ? __bfq_deactivate_entity+0x9cb/0xa50 __bfq_deactivate_entity+0x9cb/0xa50 ? update_curr+0x32f/0x5d0 bfq_deactivate_entity+0xa0/0x1d0 bfq_del_bfqq_busy+0x28a/0x420 ? resched_curr+0x116/0x1d0 ? bfq_requeue_bfqq+0x70/0x70 ? check_preempt_wakeup+0x52b/0xbc0 __bfq_bfqq_expire+0x1a2/0x270 bfq_bfqq_expire+0xd16/0x2160 ? try_to_wake_up+0x4ee/0x1260 ? bfq_end_wr_async_queues+0xe0/0xe0 ? _raw_write_unlock_bh+0x60/0x60 ? _raw_spin_lock_irq+0x81/0xe0 bfq_idle_slice_timer+0x109/0x280 ? bfq_dispatch_request+0x4870/0x4870 __hrtimer_run_queues+0x37d/0x700 ? enqueue_hrtimer+0x1b0/0x1b0 ? kvm_clock_get_cycles+0xd/0x10 ? ktime_get_update_offsets_now+0x6f/0x280 hrtimer_interrupt+0x2c8/0x740 Fix the problem by checking that the parent of the two bfqqs we are merging in bfq_setup_merge() is the same. Link: https://lore.kernel.org/linux-block/20211125172809.GC19572@quack2.suse.cz/ CC: stable(a)vger.kernel.org Fixes: 430a67f9d616 ("block, bfq: merge bursts of newly-created queues") Tested-by: "yukuai (C)" <yukuai3(a)huawei.com> Signed-off-by: Jan Kara <jack(a)suse.cz> --- block/bfq-iosched.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 6d122c28086e..7d00b21ebe5d 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -2758,6 +2758,14 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) if (process_refs == 0 || new_process_refs == 0) return NULL; + /* + * Make sure merged queues belong to the same parent. Parents could + * have changed since the time we decided the two queues are suitable + * for merging. + */ + if (new_bfqq->entity.parent != bfqq->entity.parent) + return NULL; + bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d", new_bfqq->pid); -- 2.34.1

2 years, 7 months

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FAILED: patch "[PATCH] firmware: stratix10-svc: add missing callback parameter on" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From b850b7a8b369322adf699ef48ceff4d902525c8c Mon Sep 17 00:00:00 2001 From: Ang Tien Sung <tien.sung.ang(a)intel.com> Date: Wed, 23 Feb 2022 08:41:46 -0600 Subject: [PATCH] firmware: stratix10-svc: add missing callback parameter on RSU Fix a bug whereby, the return response of parameter a1 from an SMC call is not properly set to the callback data during an INTEL_SIP_SMC_RSU_ERROR command. Link: https://lore.kernel.org/lkml/20220216081513.28319-1-tien.sung.ang@intel.com Fixes: 6b50d882d38d ("firmware: add remote status update client support") Cc: stable(a)vger.kernel.org Signed-off-by: Ang Tien Sung <tien.sung.ang(a)intel.com> Signed-off-by: Dinh Nguyen <dinguyen(a)kernel.org> Link: https://lore.kernel.org/r/20220223144146.399263-1-dinguyen@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> diff --git a/drivers/firmware/stratix10-svc.c b/drivers/firmware/stratix10-svc.c index 4bd57a908efe..8177a0fae11d 100644 --- a/drivers/firmware/stratix10-svc.c +++ b/drivers/firmware/stratix10-svc.c @@ -483,7 +483,7 @@ static int svc_normal_to_secure_thread(void *data) case INTEL_SIP_SMC_RSU_ERROR: pr_err("%s: STATUS_ERROR\n", __func__); cbdata->status = BIT(SVC_STATUS_ERROR); - cbdata->kaddr1 = NULL; + cbdata->kaddr1 = &res.a1; cbdata->kaddr2 = NULL; cbdata->kaddr3 = NULL; pdata->chan->scl->receive_cb(pdata->chan->scl, cbdata);

2 years, 7 months

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FAILED: patch "[PATCH] iio: adc: aspeed: Add divider flag to fix incorrect voltage" failed to apply to 4.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 571426631acf46e2999c7ecd1e9d048172969a43 Mon Sep 17 00:00:00 2001 From: Billy Tsai <billy_tsai(a)aspeedtech.com> Date: Mon, 21 Feb 2022 09:27:05 +0800 Subject: [PATCH] iio: adc: aspeed: Add divider flag to fix incorrect voltage reading. The formula for the ADC sampling period in ast2400/ast2500 is: ADC clock period = PCLK * 2 * (ADC0C[31:17] + 1) * (ADC0C[9:0]) When ADC0C[9:0] is set to 0 the sampling voltage will be lower than expected, because the hardware may not have enough time to charge/discharge to a stable voltage. This patch use the flag CLK_DIVIDER_ONE_BASED which will use the raw value read from the register, with the value of zero considered invalid to conform to the corrected formula. Fixes: 573803234e72 ("iio: Aspeed ADC") Reported-by: Konstantin Klubnichkin <kitsok(a)yandex-team.ru> Signed-off-by: Billy Tsai <billy_tsai(a)aspeedtech.com> Reviewed-by: Joel Stanley <joel(a)jms.id.au> Link: https://lore.kernel.org/r/20220221012705.22008-1-billy_tsai@aspeedtech.com Cc: <Stable(a)vger.kernel.org> Signed-off-by: Jonathan Cameron <Jonathan.Cameron(a)huawei.com> diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c index e939b84cbb56..0793d2474cdc 100644 --- a/drivers/iio/adc/aspeed_adc.c +++ b/drivers/iio/adc/aspeed_adc.c @@ -539,7 +539,9 @@ static int aspeed_adc_probe(struct platform_device *pdev) data->clk_scaler = devm_clk_hw_register_divider( &pdev->dev, clk_name, clk_parent_name, scaler_flags, data->base + ASPEED_REG_CLOCK_CONTROL, 0, - data->model_data->scaler_bit_width, 0, &data->clk_lock); + data->model_data->scaler_bit_width, + data->model_data->need_prescaler ? CLK_DIVIDER_ONE_BASED : 0, + &data->clk_lock); if (IS_ERR(data->clk_scaler)) return PTR_ERR(data->clk_scaler);

2 years, 7 months

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FAILED: patch "[PATCH] iio: adc: aspeed: Add divider flag to fix incorrect voltage" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 571426631acf46e2999c7ecd1e9d048172969a43 Mon Sep 17 00:00:00 2001 From: Billy Tsai <billy_tsai(a)aspeedtech.com> Date: Mon, 21 Feb 2022 09:27:05 +0800 Subject: [PATCH] iio: adc: aspeed: Add divider flag to fix incorrect voltage reading. The formula for the ADC sampling period in ast2400/ast2500 is: ADC clock period = PCLK * 2 * (ADC0C[31:17] + 1) * (ADC0C[9:0]) When ADC0C[9:0] is set to 0 the sampling voltage will be lower than expected, because the hardware may not have enough time to charge/discharge to a stable voltage. This patch use the flag CLK_DIVIDER_ONE_BASED which will use the raw value read from the register, with the value of zero considered invalid to conform to the corrected formula. Fixes: 573803234e72 ("iio: Aspeed ADC") Reported-by: Konstantin Klubnichkin <kitsok(a)yandex-team.ru> Signed-off-by: Billy Tsai <billy_tsai(a)aspeedtech.com> Reviewed-by: Joel Stanley <joel(a)jms.id.au> Link: https://lore.kernel.org/r/20220221012705.22008-1-billy_tsai@aspeedtech.com Cc: <Stable(a)vger.kernel.org> Signed-off-by: Jonathan Cameron <Jonathan.Cameron(a)huawei.com> diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c index e939b84cbb56..0793d2474cdc 100644 --- a/drivers/iio/adc/aspeed_adc.c +++ b/drivers/iio/adc/aspeed_adc.c @@ -539,7 +539,9 @@ static int aspeed_adc_probe(struct platform_device *pdev) data->clk_scaler = devm_clk_hw_register_divider( &pdev->dev, clk_name, clk_parent_name, scaler_flags, data->base + ASPEED_REG_CLOCK_CONTROL, 0, - data->model_data->scaler_bit_width, 0, &data->clk_lock); + data->model_data->scaler_bit_width, + data->model_data->need_prescaler ? CLK_DIVIDER_ONE_BASED : 0, + &data->clk_lock); if (IS_ERR(data->clk_scaler)) return PTR_ERR(data->clk_scaler);

2 years, 7 months

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FAILED: patch "[PATCH] iio: adc: aspeed: Add divider flag to fix incorrect voltage" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 571426631acf46e2999c7ecd1e9d048172969a43 Mon Sep 17 00:00:00 2001 From: Billy Tsai <billy_tsai(a)aspeedtech.com> Date: Mon, 21 Feb 2022 09:27:05 +0800 Subject: [PATCH] iio: adc: aspeed: Add divider flag to fix incorrect voltage reading. The formula for the ADC sampling period in ast2400/ast2500 is: ADC clock period = PCLK * 2 * (ADC0C[31:17] + 1) * (ADC0C[9:0]) When ADC0C[9:0] is set to 0 the sampling voltage will be lower than expected, because the hardware may not have enough time to charge/discharge to a stable voltage. This patch use the flag CLK_DIVIDER_ONE_BASED which will use the raw value read from the register, with the value of zero considered invalid to conform to the corrected formula. Fixes: 573803234e72 ("iio: Aspeed ADC") Reported-by: Konstantin Klubnichkin <kitsok(a)yandex-team.ru> Signed-off-by: Billy Tsai <billy_tsai(a)aspeedtech.com> Reviewed-by: Joel Stanley <joel(a)jms.id.au> Link: https://lore.kernel.org/r/20220221012705.22008-1-billy_tsai@aspeedtech.com Cc: <Stable(a)vger.kernel.org> Signed-off-by: Jonathan Cameron <Jonathan.Cameron(a)huawei.com> diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c index e939b84cbb56..0793d2474cdc 100644 --- a/drivers/iio/adc/aspeed_adc.c +++ b/drivers/iio/adc/aspeed_adc.c @@ -539,7 +539,9 @@ static int aspeed_adc_probe(struct platform_device *pdev) data->clk_scaler = devm_clk_hw_register_divider( &pdev->dev, clk_name, clk_parent_name, scaler_flags, data->base + ASPEED_REG_CLOCK_CONTROL, 0, - data->model_data->scaler_bit_width, 0, &data->clk_lock); + data->model_data->scaler_bit_width, + data->model_data->need_prescaler ? CLK_DIVIDER_ONE_BASED : 0, + &data->clk_lock); if (IS_ERR(data->clk_scaler)) return PTR_ERR(data->clk_scaler);

2 years, 7 months

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FAILED: patch "[PATCH] iio: adc: aspeed: Add divider flag to fix incorrect voltage" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 571426631acf46e2999c7ecd1e9d048172969a43 Mon Sep 17 00:00:00 2001 From: Billy Tsai <billy_tsai(a)aspeedtech.com> Date: Mon, 21 Feb 2022 09:27:05 +0800 Subject: [PATCH] iio: adc: aspeed: Add divider flag to fix incorrect voltage reading. The formula for the ADC sampling period in ast2400/ast2500 is: ADC clock period = PCLK * 2 * (ADC0C[31:17] + 1) * (ADC0C[9:0]) When ADC0C[9:0] is set to 0 the sampling voltage will be lower than expected, because the hardware may not have enough time to charge/discharge to a stable voltage. This patch use the flag CLK_DIVIDER_ONE_BASED which will use the raw value read from the register, with the value of zero considered invalid to conform to the corrected formula. Fixes: 573803234e72 ("iio: Aspeed ADC") Reported-by: Konstantin Klubnichkin <kitsok(a)yandex-team.ru> Signed-off-by: Billy Tsai <billy_tsai(a)aspeedtech.com> Reviewed-by: Joel Stanley <joel(a)jms.id.au> Link: https://lore.kernel.org/r/20220221012705.22008-1-billy_tsai@aspeedtech.com Cc: <Stable(a)vger.kernel.org> Signed-off-by: Jonathan Cameron <Jonathan.Cameron(a)huawei.com> diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c index e939b84cbb56..0793d2474cdc 100644 --- a/drivers/iio/adc/aspeed_adc.c +++ b/drivers/iio/adc/aspeed_adc.c @@ -539,7 +539,9 @@ static int aspeed_adc_probe(struct platform_device *pdev) data->clk_scaler = devm_clk_hw_register_divider( &pdev->dev, clk_name, clk_parent_name, scaler_flags, data->base + ASPEED_REG_CLOCK_CONTROL, 0, - data->model_data->scaler_bit_width, 0, &data->clk_lock); + data->model_data->scaler_bit_width, + data->model_data->need_prescaler ? CLK_DIVIDER_ONE_BASED : 0, + &data->clk_lock); if (IS_ERR(data->clk_scaler)) return PTR_ERR(data->clk_scaler);

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Linux-stable-mirror April 2022