Since commit e1ab9a468e3b ("i2c: imx: improve the error handling in i2c_imx_dma_request()") when booting with the DMA driver as module (such as CONFIG_FSL_EDMA=m) the following endless clk warnings are seen:

[ 153.077831] ------------[ cut here ]------------ [ 153.082528] WARNING: CPU: 0 PID: 15 at drivers/clk/clk.c:924 clk_core_disable_lock+0x18/0x24 [ 153.093077] i2c0 already disabled [ 153.096416] Modules linked in: [ 153.099521] CPU: 0 PID: 15 Comm: kworker/0:1 Tainted: G W 5.2.0+ #321 [ 153.107290] Hardware name: Freescale Vybrid VF5xx/VF6xx (Device Tree) [ 153.113772] Workqueue: events deferred_probe_work_func [ 153.118979] [<c0019560>] (unwind_backtrace) from [<c0014734>] (show_stack+0x10/0x14) [ 153.126778] [<c0014734>] (show_stack) from [<c083f8dc>] (dump_stack+0x9c/0xd4) [ 153.134051] [<c083f8dc>] (dump_stack) from [<c0031154>] (__warn+0xf8/0x124) [ 153.141056] [<c0031154>] (__warn) from [<c0031248>] (warn_slowpath_fmt+0x38/0x48) [ 153.148580] [<c0031248>] (warn_slowpath_fmt) from [<c040fde0>] (clk_core_disable_lock+0x18/0x24) [ 153.157413] [<c040fde0>] (clk_core_disable_lock) from [<c058f520>] (i2c_imx_probe+0x554/0x6ec) [ 153.166076] [<c058f520>] (i2c_imx_probe) from [<c04b9178>] (platform_drv_probe+0x48/0x98) [ 153.174297] [<c04b9178>] (platform_drv_probe) from [<c04b7298>] (really_probe+0x1d8/0x2c0) [ 153.182605] [<c04b7298>] (really_probe) from [<c04b7554>] (driver_probe_device+0x5c/0x174) [ 153.190909] [<c04b7554>] (driver_probe_device) from [<c04b58c8>] (bus_for_each_drv+0x44/0x8c) [ 153.199480] [<c04b58c8>] (bus_for_each_drv) from [<c04b746c>] (__device_attach+0xa0/0x108) [ 153.207782] [<c04b746c>] (__device_attach) from [<c04b65a4>] (bus_probe_device+0x88/0x90) [ 153.215999] [<c04b65a4>] (bus_probe_device) from [<c04b6a04>] (deferred_probe_work_func+0x60/0x90) [ 153.225003] [<c04b6a04>] (deferred_probe_work_func) from [<c004f190>] (process_one_work+0x204/0x634) [ 153.234178] [<c004f190>] (process_one_work) from [<c004f618>] (worker_thread+0x20/0x484) [ 153.242315] [<c004f618>] (worker_thread) from [<c0055c2c>] (kthread+0x118/0x150) [ 153.249758] [<c0055c2c>] (kthread) from [<c00090b4>] (ret_from_fork+0x14/0x20) [ 153.257006] Exception stack(0xdde43fb0 to 0xdde43ff8) [ 153.262095] 3fa0: 00000000 00000000 00000000 00000000 [ 153.270306] 3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 [ 153.278520] 3fe0: 00000000 00000000 00000000 00000000 00000013 00000000 [ 153.285159] irq event stamp: 3323022 [ 153.288787] hardirqs last enabled at (3323021): [<c0861c4c>] _raw_spin_unlock_irq+0x24/0x2c [ 153.297261] hardirqs last disabled at (3323022): [<c040d7a0>] clk_enable_lock+0x10/0x124 [ 153.305392] softirqs last enabled at (3322092): [<c000a504>] __do_softirq+0x344/0x540 [ 153.313352] softirqs last disabled at (3322081): [<c00385c0>] irq_exit+0x10c/0x128 [ 153.320946] ---[ end trace a506731ccd9bd703 ]---

This endless clk warnings behaviour is well explained by Andrey Smirnov:

"Allocating DMA after registering I2C adapter can lead to infinite probing loop, for example, consider the following scenario:

1. i2c_imx_probe() is called and successfully registers an I2C adapter via i2c_add_numbered_adapter()

2. As a part of i2c_add_numbered_adapter() new I2C slave devices are added from DT which results in a call to driver_deferred_probe_trigger()

3. i2c_imx_probe() continues and calls i2c_imx_dma_request() which due to lack of proper DMA driver returns -EPROBE_DEFER

4. i2c_imx_probe() fails, removes I2C adapter and returns -EPROBE_DEFER, which places it into deferred probe list

5. Deferred probe work triggered in #2 above kicks in and calls i2c_imx_probe() again thus bringing us to step #1"

So revert commit e1ab9a468e3b ("i2c: imx: improve the error handling in i2c_imx_dma_request()") and restore the old behaviour, in order to avoid regressions on existing setups.

Cc: stable@vger.kernel.org Reported-by: Andrey Smirnov andrew.smirnov@gmail.com Reported-by: Russell King linux@armlinux.org.uk Fixes: e1ab9a468e3b ("i2c: imx: improve the error handling in i2c_imx_dma_request()") Signed-off-by: Fabio Estevam festevam@gmail.com --- Changes since v2: - Revert e1ab9a468e3b ("i2c: imx: improve the error handling in i2c_imx_dma_request()")

drivers/i2c/busses/i2c-imx.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index b1b8b938d7f4..15f6cde6452f 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -273,8 +273,8 @@ static inline unsigned char imx_i2c_read_reg(struct imx_i2c_struct *i2c_imx, }

/* Functions for DMA support */ -static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx, - dma_addr_t phy_addr) +static void i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx, + dma_addr_t phy_addr) { struct imx_i2c_dma *dma; struct dma_slave_config dma_sconfig; @@ -283,7 +283,7 @@ static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,

dma = devm_kzalloc(dev, sizeof(*dma), GFP_KERNEL); if (!dma) - return -ENOMEM; + return;

dma->chan_tx = dma_request_chan(dev, "tx"); if (IS_ERR(dma->chan_tx)) { @@ -328,7 +328,7 @@ static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx, dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n", dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));

- return 0; + return;

fail_rx: dma_release_channel(dma->chan_rx); @@ -336,8 +336,6 @@ static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx, dma_release_channel(dma->chan_tx); fail_al: devm_kfree(dev, dma); - /* return successfully if there is no dma support */ - return ret == -ENODEV ? 0 : ret; }

static void i2c_imx_dma_callback(void *arg) @@ -1165,17 +1163,13 @@ static int i2c_imx_probe(struct platform_device *pdev) dev_dbg(&i2c_imx->adapter.dev, "device resources: %pR\n", res); dev_dbg(&i2c_imx->adapter.dev, "adapter name: "%s"\n", i2c_imx->adapter.name); + dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");

/* Init DMA config if supported */ - ret = i2c_imx_dma_request(i2c_imx, phy_addr); - if (ret < 0) - goto del_adapter; + i2c_imx_dma_request(i2c_imx, phy_addr);

- dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n"); return 0; /* Return OK */

-del_adapter: - i2c_del_adapter(&i2c_imx->adapter); clk_notifier_unregister: clk_notifier_unregister(i2c_imx->clk, &i2c_imx->clk_change_nb); rpm_disable: