[Why]
This patch is trying to address the issue observed when hotplug DP
daisy chain monitors.
e.g.
src-mstb-mstb-sst -> src (unplug) mstb-mstb-sst -> src-mstb-mstb-sst
(plug in again)
Once unplug a DP MST capable device, driver will call
drm_dp_mst_topology_mgr_set_mst() to disable MST. In this function,
it cleans data of topology manager while disabling mst_state. However,
it doesn't clean up the proposed_vcpis of topology manager.
If proposed_vcpi is not reset, once plug in MST daisy chain monitors
later, code will fail at checking port validation while trying to
allocate payloads.
When MST capable device is plugged in again and try to allocate
payloads by calling drm_dp_update_payload_part1(), this
function will iterate over all proposed virtual channels to see if
any proposed VCPI's num_slots is greater than 0. If any proposed
VCPI's num_slots is greater than 0 and the port which the
specific virtual channel directed to is not in the topology, code then
fails at the port validation. Since there are stale VCPI allocations
from the previous topology enablement in proposed_vcpi[], code will fail
at port validation and reurn EINVAL.
[How]
Clean up the data of stale proposed_vcpi[] and reset mgr->proposed_vcpis
to NULL while disabling mst in drm_dp_mst_topology_mgr_set_mst().
Changes since v1:
*Add on more details in commit message to describe the issue which the
patch is trying to fix
Signed-off-by: Wayne Lin <Wayne.Lin(a)amd.com>
---
drivers/gpu/drm/drm_dp_mst_topology.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index ae5809a1f19a..bf4f745a4edb 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3386,6 +3386,7 @@ static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8 dp_link_count)
int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state)
{
int ret = 0;
+ int i = 0;
struct drm_dp_mst_branch *mstb = NULL;
mutex_lock(&mgr->lock);
@@ -3446,10 +3447,21 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
/* this can fail if the device is gone */
drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0);
ret = 0;
+ mutex_lock(&mgr->payload_lock);
memset(mgr->payloads, 0, mgr->max_payloads * sizeof(struct drm_dp_payload));
mgr->payload_mask = 0;
set_bit(0, &mgr->payload_mask);
+ for (i = 0; i < mgr->max_payloads; i++) {
+ struct drm_dp_vcpi *vcpi = mgr->proposed_vcpis[i];
+
+ if (vcpi) {
+ vcpi->vcpi = 0;
+ vcpi->num_slots = 0;
+ }
+ mgr->proposed_vcpis[i] = NULL;
+ }
mgr->vcpi_mask = 0;
+ mutex_unlock(&mgr->payload_lock);
}
out_unlock:
--
2.17.1
+Xiaochen (author of the patch)
On 1/21/2020 6:26 PM, Sasha Levin wrote:
> Hi,
>
> [This is an automated email]
>
> This commit has been processed because it contains a "Fixes:" tag,
> fixing commit: c7d9aac61311 ("x86/intel_rdt/cqm: Add mkdir support for RDT monitoring").
>
> The bot has tested the following trees: v5.4.13, v4.19.97, v4.14.166.
>
> v5.4.13: Build OK!
> v4.19.97: Failed to apply! Possible dependencies:
> Unable to calculate
>
> v4.14.166: Failed to apply! Possible dependencies:
> cfd0f34e4cd5 ("x86/intel_rdt: Add diagnostics when making directories")
>
>
> NOTE: The patch will not be queued to stable trees until it is upstream.
>
> How should we proceed with this patch?
>
The purpose of this was to keep all the queues updated with
the Rx sequence numbers because unlikely yet possible
situations where queues can't understand if a specific
packet needs to be dropped or not.
Unfortunately, it was reported that this caused issues in
our DMA engine. We don't fully understand how this is related,
but this is being currently debugged. For now, just don't send
this notification to the Rx queues. This de-facto reverts my
commit 3c514bf831ac12356b695ff054bef641b9e99593:
iwlwifi: mvm: add a loose synchronization of the NSSN across Rx queues
This issue was reported here:
https://bugzilla.kernel.org/show_bug.cgi?id=204873https://bugzilla.kernel.org/show_bug.cgi?id=205001
and others maybe.
Fixes: 3c514bf831ac ("iwlwifi: mvm: add a loose synchronization of the NSSN across Rx queues")
CC: <stable(a)vger.kernel.org> # 5.3+
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach(a)intel.com>
---
drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c b/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
index 75a7af5ad7b2..8925fe5976cb 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
@@ -521,7 +521,11 @@ static void iwl_mvm_sync_nssn(struct iwl_mvm *mvm, u8 baid, u16 nssn)
.nssn_sync.nssn = nssn,
};
- iwl_mvm_sync_rx_queues_internal(mvm, (void *)¬if, sizeof(notif));
+ /*
+ * This allow to synchronize the queues, but it has been reported
+ * to cause FH issues. Don't send the notification for now.
+ * iwl_mvm_sync_rx_queues_internal(mvm, (void *)¬if, sizeof(notif));
+ */
}
#define RX_REORDER_BUF_TIMEOUT_MQ (HZ / 10)
--
2.17.1