linux-kernel - Re: [PATCH] drm/msm/dp: keep aux channel up when power of dp phy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <3d3758c19a05c4304cb03326979b382a@codeaurora.org>
Date:   Thu, 27 May 2021 08:58:44 -0700
From:   khsieh@...eaurora.org
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     agross@...nel.org, bjorn.andersson@...aro.org, robdclark@...il.com,
        sean@...rly.run, vkoul@...nel.org, abhinavk@...eaurora.org,
        aravindh@...eaurora.org, freedreno@...ts.freedesktop.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/msm/dp: keep aux channel up when power of dp phy

On 2021-05-26 21:29, Stephen Boyd wrote:
> General note, please Cc dri-devel on freedreno driver patches.
> 
> Quoting Kuogee Hsieh (2021-05-26 16:49:49)
>> Aux channel is used to perform management function and should be
>> running in parallel with main link. Therefore should only power
>> down main link and keep aux channel running when power down phy.
>> 
>> Signed-off-by: Kuogee Hsieh <khsieh@...eaurora.org>
>> ---
> 
> Does this supersede the previous patch[1] or is it in addition to?
this is the addition one.

> 
> [1]
> https://lore.kernel.org/r/1622052503-21158-1-git-send-email-khsieh@codeaurora.org
> 
>>  drivers/gpu/drm/msm/dp/dp_ctrl.c    |  4 ----
>>  drivers/phy/qualcomm/phy-qcom-qmp.c | 11 +++++++++--
>>  2 files changed, 9 insertions(+), 6 deletions(-)
> 
> Given that it touches two subsystems the merge path is questionable.
ok, will separate it out
> 
>> 
>> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c 
>> b/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> index 5115c05..5f93c64 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> @@ -1844,10 +1844,6 @@ int dp_ctrl_off_link_stream(struct dp_ctrl 
>> *dp_ctrl)
>> 
>>         phy_power_off(phy);
>> 
>> -       /* aux channel down, reinit phy */
>> -       phy_exit(phy);
>> -       phy_init(phy);
>> -
>>         DRM_DEBUG_DP("DP off link/stream done\n");
>>         return ret;
>>  }
>> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c 
>> b/drivers/phy/qualcomm/phy-qcom-qmp.c
>> index b122e63..567e32e 100644
>> --- a/drivers/phy/qualcomm/phy-qcom-qmp.c
>> +++ b/drivers/phy/qualcomm/phy-qcom-qmp.c
>> @@ -3214,12 +3214,19 @@ static int qcom_qmp_phy_power_off(struct phy 
>> *phy)
>>  {
>>         struct qmp_phy *qphy = phy_get_drvdata(phy);
>>         const struct qmp_phy_cfg *cfg = qphy->cfg;
>> +       u32 val;
>> 
>>         clk_disable_unprepare(qphy->pipe_clk);
>> 
>>         if (cfg->type == PHY_TYPE_DP) {
>> -               /* Assert DP PHY power down */
>> -               writel(DP_PHY_PD_CTL_PSR_PWRDN, qphy->pcs + 
>> QSERDES_V3_DP_PHY_PD_CTL);
>> +               /*
>> +                * Assert DP PHY LANE_0_1, LANE_2_3, PSR power down
>> +                * keep aux channel up
> 
> Maybe say "keep aux channel up until phy_exit() is called" so we know
> how long it is supposed to stay on. And just to confirm, it is on in
> phy_init(), right?
> 
yes, aux channel is on at phy_init
>> +                */
>> +               val = DP_PHY_PD_CTL_PWRDN | DP_PHY_PD_CTL_AUX_PWRDN |
>> +                       DP_PHY_PD_CTL_PLL_PWRDN | 
>> DP_PHY_PD_CTL_DP_CLAMP_EN |
>> +                       DP_PHY_PD_CTL_PSR_PWRDN;
>> +               writel(val, qphy->pcs + QSERDES_V3_DP_PHY_PD_CTL);
>>         } else {
>>                 /* PHY reset */
>>                 if (!cfg->no_pcs_sw_reset)