| Message ID | 1648656179-10347-7-git-send-email-quic_sbillaka@quicinc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add support for the eDP panel over aux_bus | expand |
Hi, On Wed, Mar 30, 2022 at 9:04 AM Sankeerth Billakanti <quic_sbillaka@quicinc.com> wrote: > > Remove the unnecessary delay in executing the EV_HPD_INIT_SETUP event. Tell me more and put it in the commit message! Why did it used to be necessary and why is it no longer necessary? Inquiring minds want to know. -Doug
Hi Doug, > On Wed, Mar 30, 2022 at 9:04 AM Sankeerth Billakanti > <quic_sbillaka@quicinc.com> wrote: > > > > Remove the unnecessary delay in executing the EV_HPD_INIT_SETUP > event. > > Tell me more and put it in the commit message! Why did it used to be > necessary and why is it no longer necessary? Inquiring minds want to know. > Okay. I will add proper description. The DP phy is shared with usb and executing the dp phy_init before the usb phy_init was causing usb devices to not function. Earlier, enabling phy_init was done when the EV_HPD_INIT_SETUP event was executed. So, we had scheduled it to execute after 10 second to let the usb driver complete the phy_init first. Kuogee made the below change to move the DP phy_init to execute after the DP is connected https://patchwork.kernel.org/project/linux-arm-msm/patch/1642531648-8448-2-git-send-email-quic_khsieh@quicinc.com/ So, there is no need for the DP driver to wait 10 seconds for the phy initialization anymore. eDP PHY is not shared with usb. So, it can be programmed anytime, hence not needing any delay. > -Doug Thank you, Sankeerth
On Mon, 4 Apr 2022 at 16:53, Sankeerth Billakanti (QUIC) <quic_sbillaka@quicinc.com> wrote: > > Hi Doug, > > > On Wed, Mar 30, 2022 at 9:04 AM Sankeerth Billakanti > > <quic_sbillaka@quicinc.com> wrote: > > > > > > Remove the unnecessary delay in executing the EV_HPD_INIT_SETUP > > event. > > > > Tell me more and put it in the commit message! Why did it used to be > > necessary and why is it no longer necessary? Inquiring minds want to know. > > > > Okay. I will add proper description. The DP phy is shared with usb and executing the > dp phy_init before the usb phy_init was causing usb devices to not function. I always wondered, how does this work for the 4-lane DP dongles, where there is no USB mode/lanes? > Earlier, enabling phy_init was done when the EV_HPD_INIT_SETUP event was executed. > So, we had scheduled it to execute after 10 second to let the usb driver complete the phy_init first. > > Kuogee made the below change to move the DP phy_init to execute after the DP is connected > https://patchwork.kernel.org/project/linux-arm-msm/patch/1642531648-8448-2-git-send-email-quic_khsieh@quicinc.com/ > > So, there is no need for the DP driver to wait 10 seconds for the phy initialization anymore. > > eDP PHY is not shared with usb. So, it can be programmed anytime, hence not needing any delay.
Hi Dmitry, > > > On Wed, Mar 30, 2022 at 9:04 AM Sankeerth Billakanti > > > <quic_sbillaka@quicinc.com> wrote: > > > > > > > > Remove the unnecessary delay in executing the EV_HPD_INIT_SETUP > > > event. > > > > > > Tell me more and put it in the commit message! Why did it used to be > > > necessary and why is it no longer necessary? Inquiring minds want to > know. > > > > > > > Okay. I will add proper description. The DP phy is shared with usb and > > executing the dp phy_init before the usb phy_init was causing usb devices > to not function. > > I always wondered, how does this work for the 4-lane DP dongles, where > there is no USB mode/lanes? > For 4 lane DP, the DP driver overrides the phy programming. For 2 lanes DP, the usb phy programming is leveraged. I believe the usb controller needs to enable both usb3 (qmp phy) and usb2 (hs phy) before DP phy_init. If one of the usb phy init fails, the usb controller will not enumerate and will cause usb2 devices (like keyboard or mouse) to not work. The usb controller probe was failing because DP was turning on (voting) a clock which was supposed to be initialized by the usb driver. We did not see any issue with DP because the programming anyway gets overwritten but due to usb controller failure, usb devices did not work. > > Earlier, enabling phy_init was done when the EV_HPD_INIT_SETUP event > was executed. > > So, we had scheduled it to execute after 10 second to let the usb driver > complete the phy_init first. > > > > Kuogee made the below change to move the DP phy_init to execute after > > the DP is connected > > https://patchwork.kernel.org/project/linux-arm-msm/patch/1642531648- > 84 > > 48-2-git-send-email-quic_khsieh@quicinc.com/ > > > > So, there is no need for the DP driver to wait 10 seconds for the phy > initialization anymore. > > > > eDP PHY is not shared with usb. So, it can be programmed anytime, hence > not needing any delay. > > > > -- > With best wishes > Dmitry
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c index 798b30b..8bafdd0 100644 --- a/drivers/gpu/drm/msm/dp/dp_display.c +++ b/drivers/gpu/drm/msm/dp/dp_display.c @@ -1526,7 +1526,7 @@ void msm_dp_irq_postinstall(struct msm_dp *dp_display) dp_hpd_event_setup(dp); - dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 100); + dp_add_event(dp, EV_HPD_INIT_SETUP, 0, 0); } void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor)
Remove the unnecessary delay in executing the EV_HPD_INIT_SETUP event. Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com> --- drivers/gpu/drm/msm/dp/dp_display.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)