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Message-ID: <84ee17f9-2597-86b6-1517-2358d443f65b@quicinc.com>
Date: Wed, 12 Jan 2022 14:17:54 -0800
From: Kuogee Hsieh <quic_khsieh@...cinc.com>
To: Stephen Boyd <swboyd@...omium.org>, <agross@...nel.org>,
<airlied@...ux.ie>, <bjorn.andersson@...aro.org>,
<daniel@...ll.ch>, <dmitry.baryshkov@...aro.org>,
<dri-devel@...ts.freedesktop.org>, <robdclark@...il.com>,
<sean@...rly.run>, <vkoul@...nel.org>
CC: <quic_abhinavk@...cinc.com>, <aravindh@...eaurora.org>,
<quic_sbillaka@...cinc.com>, <freedreno@...ts.freedesktop.org>,
<linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v11 1/4] drm/msm/dp: do not initialize phy until plugin
interrupt received
On 1/12/2022 12:00 PM, Stephen Boyd wrote:
> Quoting Kuogee Hsieh (2022-01-11 10:43:23)
>> Current DP drivers have regulators, clocks, irq and phy are grouped
>> together within a function and executed not in a symmetric manner.
>> This increase difficulty of code maintenance and limited code scalability.
>> This patch divides the driver life cycle of operation into four states,
>> resume (including booting up), dongle plugin, dongle unplugged and suspend.
>> Regulators, core clocks and irq are grouped together and enabled at resume
>> (or booting up) so that the DP controller is armed and ready to receive HPD
>> plugin interrupts. HPD plugin interrupt is generated when a dongle plugs
>> into DUT (device under test). Once HPD plugin interrupt is received, DP
>> controller will initialize phy so that dpcd read/write will function and
>> following link training can be proceeded successfully. DP phy will be
>> disabled after main link is teared down at end of unplugged HPD interrupt
>> handle triggered by dongle unplugged out of DUT. Finally regulators, code
>> clocks and irq are disabled at corresponding suspension.
0) Please note that dongles are behavior differently.
1) Apple dongle will generate plug-in interrupt only if no hdmi monitor
atatched to dongle. it will generate irq-hpd interrupt once hdmi monitor
connect to dongle later.
2) Apple dongle will generate plugged-in interrupt followed by irq-hpd
interrupt if dongle has hdmi monitor attached when connects to DUT.
3) other dongle will not generate plug-in interrupt unless dongle has
hdmi monitor attached when connects to DUT. It only generate plug-in
interrupt only and no irq-hpd interrupt generated on this case.
4) Note: phy_initialized only associated with plugged-in interrupt
5) irq-hpd interrupt must happen after plugged-in interrupt and before
unplugged interrupt
I will fill up below question with Apple dongle case with the order of
event happen timing.
> I'll write out the various scenarios
>
> #1
> dongle plugged in with HDMI cable attached
> driver probe
1) driver probe ==> core_initialized = false; phy_initialized = false;
2) dp_display_host_init() ==> core_initialized = true;
3) generate plugged-in interrupt triggers handler
4) dp_display_phy_init() ==> phy_initialized = true;
>
>
> #2
> dongle unplugged
> driver probe
1) driver probe ==> core_initialized = false; phy_initialized = false;
2) dp_display_host_init() ==> core_initialized = true;
>
> #3
> dongle plugged in without HDMI cable attached
> driver probe
1) driver probe ==> core_initialized = false; phy_initialized = false;
2) dp_display_host_init() ==> core_initialized = true;
3) generate plug-in interrupt triggers handler
4) dp_display_phy_init() ==> phy_initialized = true;
Note: same as case #1
> #4
> driver probe
> dongle plugged in without HDMI cable attached
1) driver probe ==> core_initialized = false; phy_initialized = false;
2) dp_display_host_init() ==> core_initialized = true;
3) dongle plugged in
4) generate plug-in interrupt triggers handler
5) dp_display_phy_init() ==> phy_initialized = true;
>
>
> #5
> driver probe
> dongle plugged in with HDMI cable attached
1) driver probe ==> core_initialized = false; phy_initialized = false;
2) dp_display_host_init() ==> core_initialized = true;
3) dongle plugged in
4) generate plug-in interrupt trigger handler
5) dp_display_phy_init() ==> phy_initialized = true;
Note: same as case #4
>
> #6
> driver probe
> dongle plugged in
> suspend
> resume
1) driver probe ==> core_initialized = false; phy_initialized = false;
2) dp_display_host_init() ==> core_initialized = true;
3) dongle plug in
4) generate plug-in interrupt triggers handler
5) dp_display_phy_init() ==> phy_initialized = true;
6) suspend
7) dp_display_host_deinit() ==> core_initialized = false;
8) dp_display_host_phy_exit() ==> phy_initialize = false;
9) resume
10) dp_display_host_init() ==> core_initialized = true;
11) generate plug-in interrupt
12) dp_display_phy_init() ==> phy_initialize = true;
>
> #7
> driver probe
> dongle plugged in
> suspend
> dongle unplugged
> resume
1) driver probe ==> core_initialized = false; phy_initialized = false;
2) dp_display_host_init() ==> core_initialized = true;
3) dongle plugged in
4) generate plug-in interrupt triggers handler
5) dp_display_phy_init() ==> phy_initialized = true;
6) suspend
7) dp_display_host_deinit() ==> core_initialized = false;
8) dp_display_host_phy_exit() ==> phy_initialize = false;
9) dongle unplugged
10) resume
11) dp_display_host_init() ==> core_initialized = true;
#8
driver probe
dongle plugged in without HDMI cable attached
suspend
resume
1) driver probe ==> core_initialized = false; phy_initialized = false;
2) dp_display_host_init() ==> core_initialized = true;
3) dongle plug in
4) generate plug-in interrupt triggers handler
5) dp_display_phy_init() ==> phy_initialized = true;
6) suspend
7) dp_display_host_deinit() ==> core_initialized = false;
8) dp_display_host_phy_exit() ==> phy_initialize = false;
9) resume
10) dp_display_host_init() ==> core_initialized = true;
11) generate plug-in interrupt
12) dp_display_phy_init() ==> phy_initialize = true;
NOTE: same case #6
#9
driver probe
dongle plugged in without HDMI cable attached
suspend
HDMI cable attached during suspend
resume
1) driver probe ==> core_initialized = false; phy_initialized = false;
2) dp_display_host_init() ==> core_initialized = true;
3) dongle plugged in
4) generate plug-in interrupt triggers handler
5) dp_display_phy_init() ==> phy_initialized = true;
6) suspend
7) dp_display_host_deinit() ==> core_initialized = false;
8) dp_display_host_phy_exit() ==> phy_initialize = false;
9) HDMI cable attached
10) resume
11) dp_display_host_init() ==> core_initialized = true;
12) generate plug-in interrupt
13) dp_display_phy_init() ==> phy_initialize = true;
What's the state of the phy and core initialized variable at the end of
each of these scenarios? Please fill out the truth table.
+-----------------+------------------------
| false | true |
+-----------------+------------------------
phy_initialized | | |
+-----------------+------------------------
core_initialized | | #1, |
+-----------------+------------------------
I guess we also need eDP scenarios, but that's probably simpler
#10
eDP panel connected
driver probe
1) driver probe ==> core_initialized = false; phy_initialized = false;
2) dp_display_host_init() ==> core_initialized = true;
3) generate plug-in interrupt triggers handler
4) dp_display_phy_init() ==> phy_initialized = true;
#11
eDP panel disconnected
driver probe
NOTE: eDP panel can not be disconnected
#12
eDP panel disconnected
driver probe
suspend
resume
NOTE: assume edp panel connected
1) driver probe ==> core_initialized = false; phy_initialized = false;
2) dp_display_host_init() ==> core_initialized = true;
3) generate plug-in interrupt triggers handler
4) dp_display_phy_init() ==> phy_initialized = true;
5) suspend
6) dp_display_host_deinit() ==> core_initialized = false;
7) dp_display_host_phy_exit() ==> phy_initialize = false;
8) resume
9) dp_display_host_init() ==> core_initialized = true;
10) generate plug-in interrupt
11) dp_display_phy_init() ==> phy_initialize = true;
>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
>> index 7cc4d21..f6bb4bc 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>> @@ -83,6 +83,7 @@ struct dp_display_private {
>>
>> /* state variables */
>> bool core_initialized;
>> + bool phy_initialized;
>> bool hpd_irq_on;
>> bool audio_supported;
>>
>> @@ -372,21 +373,46 @@ static int dp_display_process_hpd_high(struct dp_display_private *dp)
>> return rc;
>> }
>>
>> -static void dp_display_host_init(struct dp_display_private *dp, int reset)
>> +static void dp_display_host_phy_init(struct dp_display_private *dp)
>> {
>> - bool flip = false;
>> + DRM_DEBUG_DP("core_init=%d phy_init=%d\n",
>> + dp->core_initialized, dp->phy_initialized);
>>
>> + if (!dp->phy_initialized) {
>> + dp_ctrl_phy_init(dp->ctrl);
>> + dp->phy_initialized = true;
>> + }
>> +}
>> +
>> +static void dp_display_host_phy_exit(struct dp_display_private *dp)
>> +{
>> + DRM_DEBUG_DP("core_init=%d phy_init=%d\n",
>> + dp->core_initialized, dp->phy_initialized);
>> +
>> + if (dp->phy_initialized) {
>> + dp_ctrl_phy_exit(dp->ctrl);
>> + dp->phy_initialized = false;
>> + }
>> +}
>> +
>> +static void dp_display_host_init(struct dp_display_private *dp)
>> +{
>> DRM_DEBUG_DP("core_initialized=%d\n", dp->core_initialized);
>> if (dp->core_initialized) {
>> DRM_DEBUG_DP("DP core already initialized\n");
>> return;
>> }
>>
>> - if (dp->usbpd->orientation == ORIENTATION_CC2)
>> - flip = true;
>> + dp_power_init(dp->power, false);
>> + dp_ctrl_reset_irq_ctrl(dp->ctrl, true);
>> +
>> + /*
>> + * eDP is the embedded primary display and has its own phy
>> + * initialize phy immediately
> Question still stands why we can't wait for hpd high from the eDP panel.
> Also, I think "has its own phy" means that it's not part of a combo
> USB+DP phy? Can you please clarify?
>
>> + */
>> + if (dp->dp_display.connector_type == DRM_MODE_CONNECTOR_eDP)
>> + dp_display_host_phy_init(dp);
>>
>> - dp_power_init(dp->power, flip);
>> - dp_ctrl_host_init(dp->ctrl, flip, reset);
>> dp_aux_init(dp->aux);
>> dp->core_initialized = true;
>> }
>> @@ -1306,20 +1330,23 @@ static int dp_pm_resume(struct device *dev)
>> dp->hpd_state = ST_DISCONNECTED;
>>
>> /* turn on dp ctrl/phy */
>> - dp_display_host_init(dp, true);
>> + dp_display_host_init(dp);
>>
>> dp_catalog_ctrl_hpd_config(dp->catalog);
>>
>> - /*
>> - * set sink to normal operation mode -- D0
>> - * before dpcd read
>> - */
>> - dp_link_psm_config(dp->link, &dp->panel->link_info, false);
>>
>> if (dp_catalog_link_is_connected(dp->catalog)) {
>> + /*
>> + * set sink to normal operation mode -- D0
>> + * before dpcd read
>> + */
>> + dp_display_host_phy_init(dp);
>> + dp_link_psm_config(dp->link, &dp->panel->link_info, false);
>> sink_count = drm_dp_read_sink_count(dp->aux);
>> if (sink_count < 0)
>> sink_count = 0;
>> +
>> + dp_display_host_phy_exit(dp);
> Why is the phy exited on resume when the link is still connected? Is
> this supposed to be done only when the sink_count is 0? And how does
> this interact with eDP where the phy is initialized by the call to
> dp_display_host_init() earlier in this function.
>
>> }
>>
>> dp->link->sink_count = sink_count;
>> @@ -1366,6 +1393,8 @@ static int dp_pm_suspend(struct device *dev)
>> dp_display_host_deinit(dp);
>> }
>>
>> + dp_display_host_phy_exit(dp);
>> +
>> dp->hpd_state = ST_SUSPENDED;
>>
>> /* host_init will be called at pm_resume */
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