From patchwork Fri Mar 7 04:34:42 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dmitry Baryshkov X-Patchwork-Id: 871314 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5E19AC2E0; Fri, 7 Mar 2025 04:34:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741322094; cv=none; b=tQWzfItF63ny8YVMrLD7E/OoQz5aD+xP9tvKJHyl9B6bjkVWBoNI7qtsrDYxXr2mY8PvomsdoNQAGYVpQ2Ac1U5y5Amuqh2NEWLLGKdx9OhrilnFQHVdBM7AuvDOWpteaeIM4aBd86++dDEjma02eXQlUpeuBNguyUYfUS+sOik= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741322094; c=relaxed/simple; bh=XqzhyeJqcijzc1zEWnFHc8CXWW9TaUwdVzABORTsWzg=; h=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc; b=b4dmAo4yYowpBArIeJ97Ty98j4h7DteefRehtO5r2lEkXa149MsZ7aIDruZpWkS5yVii/0Fk+E1EKxTtmisYFulHPlmEus/BsXqEgUNRzJq2Tphqnh6QX/W8pGe7/vSNqBKFwIJuKrWYrgQ0KFMcr226gRBtNqBGrTMldjKRf1c= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=s+HhjOhS; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="s+HhjOhS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35F21C4CED1; Fri, 7 Mar 2025 04:34:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741322093; bh=XqzhyeJqcijzc1zEWnFHc8CXWW9TaUwdVzABORTsWzg=; h=From:Subject:Date:To:Cc:From; b=s+HhjOhSqHORZRdCgtb8Vrv/rRuiWnb96ZQPANjE1MyLwf3qdFWc2jI5VqiZa8eLB rD1b7oK29o0X37aFgrq8IN7nhINe9omVacWzB1cRMkwuo/SdpjKFNyeexIIPWkrzvB 6ETBorUlap+aEeFVdMzQs9lrybWuEK8ArkvbW48OaEc6E9wMJYRWulm31uDNeZGiR0 LwuAYUWGW/uDhdQZUGNrZ4xjC81nKYrfrCmTW8kPQWKaPG6l+nZGBVZ7gj4l1EByIT f8d4wcY/gZVqdKMs/XKdc7OXjzmKrTaJBsNyBunLaPyoVNRZWA6moIo3coTUSjn4BF 2Y+dPoHVcvD4w== From: Dmitry Baryshkov Subject: [PATCH RFC v3 0/7] drm/display: dp: add new DPCD access functions Date: Fri, 07 Mar 2025 06:34:42 +0200 Message-Id: <20250307-drm-rework-dpcd-access-v3-0-9044a3a868ee@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=H4sIAGJ3ymcC/3XOwQrCMAwG4FeRnq2k2dzQkyD4AF7Fw5ZmW1HXk UpVxt7dsot42PFP+L9kVIHFcVD71aiEowvO9ylk65Wirupb1s6mrBAwN5gZbeWhhV9ebtoOZHV FxCHoGhpCzktbmEyl8iDcuPcMX9T5dFTXNOxceHr5zMeimVfJ3YIx5ZIbjQZdNgQIDLmt6XB3f SV+46WdzYg/J4PF/yImJ7c7LAAbKsn+OdM0fQEd0r1rCgEAAA== 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 , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Xinliang Liu , Tian Tao , Xinwei Kong , Sumit Semwal , Yongqin Liu , John Stultz Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, Jani Nikula X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2883; i=dmitry.baryshkov@linaro.org; h=from:subject:message-id; bh=XqzhyeJqcijzc1zEWnFHc8CXWW9TaUwdVzABORTsWzg=; b=owEBbQGS/pANAwAKAYs8ij4CKSjVAcsmYgBnyndlMsf/JrFPSmdbYWWLvhwHDkT/ieTkTXN9/ lqE5dH+wNGJATMEAAEKAB0WIQRMcISVXLJjVvC4lX+LPIo+Aiko1QUCZ8p3ZQAKCRCLPIo+Aiko 1aKhCACjQw5F7YO5gtzvIHSaGtZo4Y/5aGzxeTxD0OMUp/5hT2oTXrms082iYP0AiH6KDcY4cRH cd3zg/fRgPvw+3Pnwe88wo/9F9RGhnuyAzfT+b76GOoq3qiO6xws9hNIM/+p+uQ0quL67unGB7/ 8PJc5scnCbK2hQcuNiYvuD2+Zy3SQn2wz4LaZHuLOo9WrMlIpiwz0iFIaXWJPG0nfCgYTbp15g3 A0mofYnAkZSoMSG4BUHj4Wje+l7WpPdL2AD9Pd1BYoFabjJX6gnm2HhidAkS7cXc4tU7/onNjrc 2IRbVF+vSZdWm+C9yJ/TubcGS1ZPe8N0m4SoukasvViWrDel 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. Implement new helpers using existing functions to ensure backwards compatibility and to assess necessity to handle incomplete reads on a global scale. Currently only one possible place has been identified, dp-aux-dev, which needs to handle possible holes in DPCD. 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 v3: - Fixed cover letter (Jani) - Added intel-gfx and intel-xe to get the series CI-tested (Jani) - Link to v2: https://lore.kernel.org/r/20250301-drm-rework-dpcd-access-v2-0-4d92602fc7cd@linaro.org 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: 565351ae7e0cee80e9b5ed84452a5b13644ffc4d change-id: 20241231-drm-rework-dpcd-access-b0fc2e47d613 Best regards,