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Sat, 01 Mar 2025 12:39:45 -0800 (PST) From: Dmitry Baryshkov Subject: [PATCH RFC v2 0/7] drm/display: dp: add new DPCD access functions Date: Sat, 01 Mar 2025 22:39:35 +0200 Message-Id: <20250301-drm-rework-dpcd-access-v2-0-4d92602fc7cd@linaro.org> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-B4-Tracking: v=1; b=H4sIAIdww2cC/3WNwQ6CMBBEf4Xs2TXdgpJ4MjHxA7waDrBdoFEo2 RrUEP7dhrvHN5N5s0AU9RLhlC2gMvvow5jA7jLgvh47Qe8SgzW2IJsTOh1Q5R30gW5ihzWzxIi NadlKUboj5ZDGk0rrP5v4DrfrBaoU9j6+gn63s5m2KnkPhqj8550JDZYtG2vEFK7h89OPtYZ90 A6qdV1/0cFrTMIAAAA= X-Change-ID: 20241231-drm-rework-dpcd-access-b0fc2e47d613 To: Lyude Paul , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Clark , Abhinav Kumar , Sean Paul , Marijn Suijten , Jani Nikula Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, Jani Nikula X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2489; i=dmitry.baryshkov@linaro.org; h=from:subject:message-id; bh=hZO10I/DG1vyNEkMu0QuAX4yVnOsd0XWkUBtv8xUeKY=; b=owEBbQGS/pANAwAKAYs8ij4CKSjVAcsmYgBnw3CPdZnNfQzvTNfvm624R2DWUI4vkz/LXqKhA MuM0BvXi2OJATMEAAEKAB0WIQRMcISVXLJjVvC4lX+LPIo+Aiko1QUCZ8NwjwAKCRCLPIo+Aiko 1QN0B/40RX6HQ2yZIjBR9Q+Kcc6Vhtt8O6fvz6k27NSg1LWXTHHAG9lsjsPgR8mETncfA7+cL1S TTp16ccbJW9iUoivWOUq1eKMMRXqUTZKBi69cOmyu7nRBcEKWEVMfQFDiquX42fi3qlZdAc5W7N TLVR7V6hYRK06fccrNzVGwqSzmLy6vRE6KC+Ut3tBzGxIBqMYqQFbdaWYQDEwoD7OcuC4Zu//cg OL+6n/FYhotBL57blqx31J7sqNOSR0uuau1xDo4xe3Oh8u63mNtlr0C46XXf7Z5K4axtWvhx1Tb /f78njkOdV1oI6Cqoy24Hq174DyVXm4sJVQiIiAGyA2AgyAx X-Developer-Key: i=dmitry.baryshkov@linaro.org; a=openpgp; fpr=8F88381DD5C873E4AE487DA5199BF1243632046A 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. Signed-off-by: Dmitry Baryshkov --- 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@linaro.org --- 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,