Re: [PATCH RFC v2 0/7] drm/display: dp: add new DPCD access functions

[Jani Nikula]

On Thu, 06 Mar 2025, Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote:
> On Sat, 01 Mar 2025, Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> wrote:
>> Existing DPCD access functions return an error code or the number of
>> bytes being read / write in case of partial access. However a lot of
>> drivers either (incorrectly) ignore partial access or mishandle error
>> codes. In other cases this results in a boilerplate code which compares
>> returned value with the size.
>>
>> As suggested by Jani implement new set of DPCD access helpers, which
>> ignore partial access, always return 0 or an error code. Reimplement
>> existing helpers using the new functions to ensure backwards
>> compatibility.
>
> I think that description is for earlier versions of the series, it's the
> other way round now.
>
> Regardless, glanced through the series quickly, I like it, this is
>
> Acked-by: Jani Nikula <jani.nikula@xxxxxxxxx>

PS. If you need to send another round, please Cc: intel-gfx and intel-xe
to run this through CI for both i915 and xe drivers. Thanks!

>
>
>>
>> This series targets only the DRM helpers code. If the approach is found
>> to be acceptable, each of the drivers should be converted on its own.
>>
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
>> ---
>> Changes in v2:
>> - Reimplemented new helpers using old ones (Lyude)
>> - Reworked the drm_dp_dpcd_read_link_status() patch (Lyude)
>> - Dropped the dp-aux-dev patch (Jani)
>> - Link to v1: https://lore.kernel.org/r/20250117-drm-rework-dpcd-access-v1-0-7fc020e04dbc@xxxxxxxxxx
>>
>> ---
>> Dmitry Baryshkov (7):
>>       drm/display: dp: implement new access helpers
>>       drm/display: dp: change drm_dp_dpcd_read_link_status() return value
>>       drm/display: dp: use new DCPD access helpers
>>       drm/display: dp-aux-dev: use new DCPD access helpers
>>       drm/display: dp-cec: use new DCPD access helpers
>>       drm/display: dp-mst-topology: use new DCPD access helpers
>>       drm/display: dp-tunnel: use new DCPD access helpers
>>
>>  drivers/gpu/drm/amd/amdgpu/atombios_dp.c           |   8 +-
>>  .../gpu/drm/bridge/cadence/cdns-mhdp8546-core.c    |   2 +-
>>  drivers/gpu/drm/display/drm_dp_aux_dev.c           |  12 +-
>>  drivers/gpu/drm/display/drm_dp_cec.c               |  37 ++-
>>  drivers/gpu/drm/display/drm_dp_helper.c            | 307 +++++++++------------
>>  drivers/gpu/drm/display/drm_dp_mst_topology.c      | 105 ++++---
>>  drivers/gpu/drm/display/drm_dp_tunnel.c            |  20 +-
>>  drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c       |   4 +-
>>  drivers/gpu/drm/msm/dp/dp_ctrl.c                   |  24 +-
>>  drivers/gpu/drm/msm/dp/dp_link.c                   |  18 +-
>>  drivers/gpu/drm/radeon/atombios_dp.c               |   8 +-
>>  include/drm/display/drm_dp_helper.h                |  92 +++++-
>>  12 files changed, 322 insertions(+), 315 deletions(-)
>> ---
>> base-commit: c0eb65494e59d9834af7cbad983629e9017b25a1
>> change-id: 20241231-drm-rework-dpcd-access-b0fc2e47d613
>>
>> Best regards,

-- 
Jani Nikula, Intel