Attachment 145548 Details for Bug 111749 – Patch to modify drm_dp_dpcd_read to include single read

[patch] Patch to modify drm_dp_dpcd_read to include single read

0002-CHROMIUM-drm-modify-drm_dp_dpcd_read-to-include-sing.patch (text/plain), 2.46 KB, created by gaurav.k.singh on 2019-09-27 16:21:26 UTC

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Creator: gaurav.k.singh

Created: 2019-09-27 16:21:26 UTC

Size: 2.46 KB

patch

obsolete

>From 9a802aba8446799b522c3926f866b79492d07dcc Mon Sep 17 00:00:00 2001
>From: Gaurav K Singh <gaurav.k.singh@intel.com>
>Date: Thu, 26 Sep 2019 10:20:52 +0530
>Subject: [PATCH 2/2] CHROMIUM: drm: modify drm_dp_dpcd_read to include single
> read
>
>Add single read functionality to drm_dp_dpcd_read, to be executed
>conditionally based on the value in /sys/kernel/debug/dri/dpcd_read_once
>
>Single read is required to satisfy AUX channel sequencing when
>updating TCON firmware in display panels.
>
>BUG=None
>TEST=Pick patch, build, boot
>	- Set value in file to Y, and successfully execute TCON
>	  firmware update script
>	- Set value in file to N, and verify script fails to update
>	  TCON firmware
>
>Change-Id: Id7e926fce91a1bd5ae769423508146c49d4207a8
>Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
>---
> drivers/gpu/drm/drm_dp_helper.c | 15 ++++++++++-----
> include/drm/drm_drv.h           |  1 +
> 2 files changed, 11 insertions(+), 5 deletions(-)
>
>diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
>index 871abbc00b79..513df9b8f618 100644
>--- a/drivers/gpu/drm/drm_dp_helper.c
>+++ b/drivers/gpu/drm/drm_dp_helper.c
>@@ -277,14 +277,19 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
> 	 * up, so there is no particularly good place to do the workaround.
> 	 * We just have to do it before any DPCD access and hope that the
> 	 * monitor doesn't power down exactly after the throw away read.
>+	 *
>+	 * In order to support updates of the TCON firmware in display panels
>+	 * a single read must be supported as well. Choose single or double
>+	 * based on the value stored in the drm debugfs file dpcd_read_once
> 	 */
>-	ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV, buffer,
>+	if (!dpcd_read_once) {
>+		ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV, buffer,
> 				 1);
>-	if (ret != 1)
>-		goto out;
>+		if (ret != 1)
>+			goto out;
>+	}
> 
>-	ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer,
>-				 size);
>+	ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer, size);
> 
> out:
> 	drm_dp_dump_access(aux, DP_AUX_NATIVE_READ, offset, buffer, ret);
>diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
>index 7eda22464b7f..a14e573d65be 100644
>--- a/include/drm/drm_drv.h
>+++ b/include/drm/drm_drv.h
>@@ -613,6 +613,7 @@ struct drm_driver {
> 
> extern unsigned int drm_debug;
> extern bool drm_master_relax;
>+extern bool dpcd_read_once;
> 
> int drm_dev_init(struct drm_device *dev,
> 		 struct drm_driver *driver,
>-- 
>1.9.1
>

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Attachments on bug 111749: 145431 | 145432 | 145460 | 145489 | 145509 | 145547 | 145548 | 145549

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