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

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Message-ID: <ctla3nt6o3osdxek63zyidyuofzgq3mgshh2azong3ntcqevhi@3rrzr3hrzbor>
Date: Thu, 23 Jan 2025 00:14:35 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Rob Clark <robdclark@...il.com>, 
	Abhinav Kumar <quic_abhinavk@...cinc.com>, Sean Paul <sean@...rly.run>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, Jani Nikula <jani.nikula@...ux.intel.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org
Subject: Re: [PATCH RFC 0/7] drm/display: dp: add new DPCD access functions

On Fri, Jan 17, 2025 at 10:56:35AM +0200, Dmitry Baryshkov 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.
> 
> 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.

Gracious ping for the series, it's been posted a week ago.

> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
> Dmitry Baryshkov (7):
>       drm/display: dp: change drm_dp_dpcd_read_link_status() return
>       drm/display: dp: implement new access helpers
>       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/display/drm_dp_aux_dev.c      |  12 +-
>  drivers/gpu/drm/display/drm_dp_cec.c          |  37 ++-
>  drivers/gpu/drm/display/drm_dp_helper.c       | 345 +++++++++++---------------
>  drivers/gpu/drm/display/drm_dp_mst_topology.c | 132 +++++-----
>  drivers/gpu/drm/display/drm_dp_tunnel.c       |  20 +-
>  drivers/gpu/drm/msm/dp/dp_ctrl.c              |  45 ++--
>  drivers/gpu/drm/msm/dp/dp_link.c              |  17 +-
>  include/drm/display/drm_dp_helper.h           |  81 +++++-
>  include/drm/display/drm_dp_mst_helper.h       |  10 +-
>  9 files changed, 354 insertions(+), 345 deletions(-)
> ---
> base-commit: 440aaf479c9aaf5ecea9a463eb826ec243d5f1cf
> change-id: 20241231-drm-rework-dpcd-access-b0fc2e47d613
> 
> Best regards,
> -- 
> Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> 

-- 
With best wishes
Dmitry