From: Stephen Boyd <swboyd@chromium.org>
To: Kuogee Hsieh <khsieh@codeaurora.org>,
dri-devel@lists.freedesktop.org, robdclark@gmail.com,
sean@poorly.run
Cc: abhinavk@codeaurora.org, aravindh@codeaurora.org,
airlied@linux.ie, daniel@ffwll.ch, bjorn.andersson@linaro.org,
linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 7/7] drm/msm/dp: retrain link when loss of symbol lock detected
Date: Thu, 8 Jul 2021 07:21:52 +0000 [thread overview]
Message-ID: <CAE-0n51U8faPjxfFcd3uuOk27urR2rCSGhg1Kat1AO6LLixYTw@mail.gmail.com> (raw)
In-Reply-To: <1625592020-22658-8-git-send-email-khsieh@codeaurora.org>
Quoting Kuogee Hsieh (2021-07-06 10:20:20)
> Main link symbol locked is achieved at end of link training 2. Some
> dongle main link symbol may become unlocked again if host did not end
> link training soon enough after completion of link training 2. Host
> have to re train main link if loss of symbol lock detected before
> end link training so that the coming video stream can be transmitted
> to sink properly.
>
> Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
I guess this is a fix for the original driver, so it should be tagged
with Fixes appropriately.
> ---
> drivers/gpu/drm/msm/dp/dp_ctrl.c | 34 ++++++++++++++++++++++++++++++++++
> 1 file changed, 34 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> index 0cb01a9..e616ab2 100644
> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
> @@ -1661,6 +1661,25 @@ static bool dp_ctrl_any_lane_cr_lose(struct dp_ctrl_private *ctrl,
> return false;
> }
>
> +static bool dp_ctrl_loss_symbol_lock(struct dp_ctrl_private *ctrl)
> +{
> + u8 link_status[6];
Can we use link_status[DP_LINK_STATUS_SIZE] instead?
> + u8 status;
> + int i;
> + int lane = ctrl->link->link_params.num_lanes;
s/lane/num_lanes/
would make the code easier to read
> +
> + dp_ctrl_read_link_status(ctrl, link_status);
> +
> + for (i = 0; i < lane; i++) {
> + status = link_status[i / 2];
> + status >>= ((i % 2) * 4);
> + if (!(status & DP_LANE_SYMBOL_LOCKED))
> + return true;
> + }
> +
> + return false;
> +}
> +
> int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
> {
> int rc = 0;
> @@ -1777,6 +1796,17 @@ int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl)
> return rc;
> }
>
> +static int dp_ctrl_link_retrain(struct dp_ctrl_private *ctrl)
> +{
> + int ret = 0;
Please drop init of ret.
> + u8 cr_status[2];
> + int training_step = DP_TRAINING_NONE;
> +
> + ret = dp_ctrl_setup_main_link(ctrl, cr_status, &training_step);
as it is assigned here.
> +
> + return ret;
And indeed, it could be 'return dp_ctrl_setup_main_link()' instead.
> +}
> +
> int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl)
> {
> int ret = 0;
> @@ -1802,6 +1832,10 @@ int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl)
> }
> }
>
> + /* if loss symbol lock happen, then retaining the link */
retain or retrain? The comment seems to be saying what the code says "if
loss retrain", so the comment is not very useful.
> + if (dp_ctrl_loss_symbol_lock(ctrl))
> + dp_ctrl_link_retrain(ctrl);
> +
> /* stop txing train pattern to end link training */
> dp_ctrl_clear_training_pattern(ctrl);
>
next prev parent reply other threads:[~2021-07-08 7:21 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-06 17:20 [PATCH 0/7] add fixes to pass DP Link Layer compliance test cases Kuogee Hsieh
2021-07-06 17:20 ` [PATCH 1/7] drm/msm/dp: use dp_ctrl_off_link_stream during PHY compliance test run Kuogee Hsieh
2021-07-08 7:03 ` Stephen Boyd
2021-07-08 21:33 ` khsieh
2021-07-06 17:20 ` [PATCH 2/7] drm/msm/dp: reduce link rate if failed at link training 1 Kuogee Hsieh
2021-07-08 7:33 ` Stephen Boyd
2021-07-09 17:46 ` khsieh
2021-07-15 18:59 ` Stephen Boyd
2021-07-06 17:20 ` [PATCH 3/7] drm/msm/dp: reset aux controller after dp_aux_cmd_fifo_tx() failed Kuogee Hsieh
2021-07-08 7:34 ` Stephen Boyd
2021-07-08 21:59 ` khsieh
2021-07-06 17:20 ` [PATCH 4/7] drm/msm/dp: replug event is converted into an unplug followed by an plug events Kuogee Hsieh
2021-07-08 20:56 ` Stephen Boyd
2021-07-06 17:20 ` [PATCH 5/7] drm/msm/dp: return correct edid checksum after corrupted edid checksum read Kuogee Hsieh
2021-07-08 7:14 ` Stephen Boyd
2021-07-09 18:16 ` khsieh
2021-07-06 17:20 ` [PATCH 6/7] drm/msm/dp: do not end dp link training until video is ready Kuogee Hsieh
2021-07-06 17:20 ` [PATCH 7/7] drm/msm/dp: retrain link when loss of symbol lock detected Kuogee Hsieh
2021-07-08 7:21 ` Stephen Boyd [this message]
2021-07-09 17:16 ` khsieh
2021-07-15 19:00 ` Stephen Boyd
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAE-0n51U8faPjxfFcd3uuOk27urR2rCSGhg1Kat1AO6LLixYTw@mail.gmail.com \
--to=swboyd@chromium.org \
--cc=abhinavk@codeaurora.org \
--cc=airlied@linux.ie \
--cc=aravindh@codeaurora.org \
--cc=bjorn.andersson@linaro.org \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=freedreno@lists.freedesktop.org \
--cc=khsieh@codeaurora.org \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=robdclark@gmail.com \
--cc=sean@poorly.run \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).