From: khsieh@codeaurora.org
To: Stephen Boyd <swboyd@chromium.org>
Cc: dri-devel@lists.freedesktop.org, robdclark@gmail.com,
sean@poorly.run, 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: Fri, 09 Jul 2021 10:16:52 -0700 [thread overview]
Message-ID: <e6375232222bc357897b62c1752c06d8@codeaurora.org> (raw)
In-Reply-To: <CAE-0n51U8faPjxfFcd3uuOk27urR2rCSGhg1Kat1AO6LLixYTw@mail.gmail.com>
On 2021-07-08 00:21, Stephen Boyd wrote:
> 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.
Actually, this is fix on patch #6 : drm/msm/dp: do not end dp link
training until video is ready
Should i merge patch #6 and #7 together?
Or can you suggest what should I do?
>
>> ---
>> 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:[~2021-07-09 17:17 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
2021-07-09 17:16 ` khsieh [this message]
2021-07-15 19:00 ` Stephen Boyd
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