On Tue, 04 Feb 2025, Imre Deak <imre.deak@xxxxxxxxx> wrote:
> On Tue, Feb 04, 2025 at 05:49:25PM +0200, Jani Nikula wrote:
>> Passing 0 as the step only works when there are other reasons to break
>> out of the BPP loop in intel_dp_mtp_tu_compute_config(). Otherwise, an
>> infinite loop might occur. Fix it by explicitly checking for 0 step.
>>
>> Fixes: ef0a0757bbea ("drm/i915/dp: compute config for 128b/132b SST w/o DSC")
>> Reported-by: Imre Deak <imre.deak@xxxxxxxxx>
>> Closes: https://lore.kernel.org/r/Z6I0knh2Kt5T0JrT@xxxxxxxxxxxxxxxxxxxxxxx
>> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
>
> Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx>
Pushed to din, thanks for the review!
>
>> ---
>>
>> Note: This needs a backport with (!step) for -rc1.
>> ---
>> drivers/gpu/drm/i915/display/intel_dp_mst.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
>> index 95abc6ea85eb..1587be5cd0a7 100644
>> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
>> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
>> @@ -353,6 +353,10 @@ int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp,
>>
>> break;
>> }
>> +
>> + /* Allow using zero step to indicate one try */
>> + if (!bpp_step_x16)
>> + break;
>> }
>>
>> if (slots < 0) {
>> --
>> 2.39.5
>>
--
Jani Nikula, Intel
