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

[Jani Nikula]

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>


>
> 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