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Message-ID: <832a55a6-9914-a5f1-5bef-30421e47181d@quicinc.com>
Date: Fri, 25 Aug 2023 13:44:46 -0700
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Kuogee Hsieh <quic_khsieh@...cinc.com>, <robdclark@...il.com>,
<sean@...rly.run>, <swboyd@...omium.org>, <dianders@...omium.org>,
<vkoul@...nel.org>, <daniel@...ll.ch>, <airlied@...il.com>,
<agross@...nel.org>, <dmitry.baryshkov@...aro.org>,
<andersson@...nel.org>, <marijn.suijten@...ainline.org>
CC: <quic_jesszhan@...cinc.com>, <quic_sbillaka@...cinc.com>,
<freedreno@...ts.freedesktop.org>,
<dri-devel@...ts.freedesktop.org>, <linux-arm-msm@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] drm/msm/dp: do not reinitialize phy unless retry
during link training
On 8/8/2023 3:19 PM, Kuogee Hsieh wrote:
> DP PHY re-initialization done using dp_ctrl_reinitialize_mainlink() will
> cause PLL unlocked initially and then PLL gets locked at the end of
> initialization. PLL_UNLOCKED interrupt will fire during this time if the
> interrupt mask is enabled.
There should be a line break here.
> However currently DP driver link training implementation incorrectly
> re-initializes PHY unconditionally during link training as the PHY was
> already configured in dp_ctrl_enable_mainlink_clocks().
>
> Fix this by re-initializing the PHY only if the previous link training
> failed.
>
> [drm:dp_aux_isr] *ERROR* Unexpected DP AUX IRQ 0x01000000 when not busy
>
> Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
> Closes: https://gitlab.freedesktop.org/drm/msm/-/issues/30
> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
I tested and confirm that without this patch, I see this spam atleast
once per reboot but after this patch, I have not seen this for 5
consecutive reboots.
Hence,
Tested-by: Abhinav Kumar <quic_abhinavk@...cinc.com> # sc7280
Looking at the code flow, the dp_ctrl_reinitialize_mainlink() certainly
looks redundant where it is, considering that the clks were enabled just
a couple of lines above in dp_ctrl_enable_mainlink_clocks().
Hence with the minor fix in the commit,
Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> ---
> drivers/gpu/drm/msm/dp/dp_ctrl.c | 13 ++++++-------
> 1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index a7a5c7e..77a8d93 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -1774,13 +1774,6 @@ int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
> return rc;
>
> while (--link_train_max_retries) {
> - rc = dp_ctrl_reinitialize_mainlink(ctrl);
> - if (rc) {
> - DRM_ERROR("Failed to reinitialize mainlink. rc=%d\n",
> - rc);
> - break;
> - }
> -
> training_step = DP_TRAINING_NONE;
> rc = dp_ctrl_setup_main_link(ctrl, &training_step);
> if (rc == 0) {
> @@ -1832,6 +1825,12 @@ int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
> /* stop link training before start re training */
> dp_ctrl_clear_training_pattern(ctrl);
> }
> +
> + rc = dp_ctrl_reinitialize_mainlink(ctrl);
> + if (rc) {
> + DRM_ERROR("Failed to reinitialize mainlink. rc=%d\n", rc);
> + break;
> + }
> }
>
> if (ctrl->link->sink_request & DP_TEST_LINK_PHY_TEST_PATTERN)
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