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SubjectRe: [PATCH v3] drm/dp_mst: Fix return code on sideband message failure
On 2021-07-07 01:37, Jani Nikula wrote:
> On Tue, 06 Jul 2021, Kuogee Hsieh <khsieh@codeaurora.org> wrote:
>> From: Rajkumar Subbiah <rsubbia@codeaurora.org>
>>
>> Commit 2f015ec6eab6 ("drm/dp_mst: Add sideband down request tracing +
>> selftests") added some debug code for sideband message tracing. But
>> it seems to have unintentionally changed the behavior on sideband
>> message
>> failure. It catches and returns failure only if DRM_UT_DP is enabled.
>> Otherwise it ignores the error code and returns success. So on an MST
>> unplug, the caller is unaware that the clear payload message failed
>> and
>> ends up waiting for 4 seconds for the response. Fixes the issue by
>> returning the proper error code.
>>
>> Changes in V2:
>> -- Revise commit text as review comment
>> -- add Fixes text
>>
>> Changes in V3:
>> -- remove "unlikely" optimization
>>
>> Fixes: 2f015ec6eab6 ("drm/dp_mst: Add sideband down request tracing +
>> selftests")
>>
>> Signed-off-by: Rajkumar Subbiah <rsubbia@codeaurora.org>
>> Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
>>
>> Reviewed-by: Stephen Boyd <swboyd@chromium.org>
>
> Reviewed-by: Jani Nikula <jani.nikula@intel.com>
>
>
>> ---
Lyude,
Any comments from you?
Thanks,

>> drivers/gpu/drm/drm_dp_mst_topology.c | 10 ++++++----
>> 1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
>> b/drivers/gpu/drm/drm_dp_mst_topology.c
>> index 1590144..df91110 100644
>> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
>> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
>> @@ -2887,11 +2887,13 @@ static int process_single_tx_qlock(struct
>> drm_dp_mst_topology_mgr *mgr,
>> idx += tosend + 1;
>>
>> ret = drm_dp_send_sideband_msg(mgr, up, chunk, idx);
>> - if (unlikely(ret) && drm_debug_enabled(DRM_UT_DP)) {
>> - struct drm_printer p = drm_debug_printer(DBG_PREFIX);
>> + if (ret) {
>> + if (drm_debug_enabled(DRM_UT_DP)) {
>> + struct drm_printer p = drm_debug_printer(DBG_PREFIX);
>>
>> - drm_printf(&p, "sideband msg failed to send\n");
>> - drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
>> + drm_printf(&p, "sideband msg failed to send\n");
>> + drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
>> + }
>> return ret;
>> }

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