Re: [PATCH v8 2/4] drm/msm/dp: Support only IRQ_HPD and REPLUG interrupts for eDP

Hi,

On Thu, Apr 21, 2022 at 7:37 AM Sankeerth Billakanti quic_sbillaka@quicinc.com wrote:

The panel-edp enables the eDP panel power during probe, get_modes and pre-enable. The eDP connect and disconnect interrupts for the eDP/DP controller are directly dependent on panel power. As eDP display can be assumed as always connected, the controller driver can skip the eDP connect and disconnect interrupts. Any disruption in the link status will be indicated via the IRQ_HPD interrupts.

So, the eDP controller driver can just enable the IRQ_HPD and replug interrupts. The DP controller driver still needs to enable all the interrupts.

Signed-off-by: Sankeerth Billakanti quic_sbillaka@quicinc.com

Changes in v8:

• add comment explaining the interrupt status return

Changes in v7:

• reordered the patch in the series
• modified the return statement for isr
• connector check modified to just check for eDP

drivers/gpu/drm/msm/dp/dp_catalog.c | 18 ++++++++++++------ drivers/gpu/drm/msm/dp/dp_display.c | 22 +++++++++++++++++++++- 2 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.c b/drivers/gpu/drm/msm/dp/dp_catalog.c index fac815f..3a298e9 100644 --- a/drivers/gpu/drm/msm/dp/dp_catalog.c +++ b/drivers/gpu/drm/msm/dp/dp_catalog.c @@ -569,10 +569,6 @@ void dp_catalog_ctrl_hpd_config(struct dp_catalog *dp_catalog)

    u32 reftimer = dp_read_aux(catalog, REG_DP_DP_HPD_REFTIMER);

•   /* enable HPD plug and unplug interrupts */
  

•   dp_catalog_hpd_config_intr(dp_catalog,
  

•           DP_DP_HPD_PLUG_INT_MASK | DP_DP_HPD_UNPLUG_INT_MASK, true);
  

•   /* Configure REFTIMER and enable it */
    reftimer |= DP_DP_HPD_REFTIMER_ENABLE;
    dp_write_aux(catalog, REG_DP_DP_HPD_REFTIMER, reftimer);
  

@@ -599,13 +595,23 @@ u32 dp_catalog_hpd_get_intr_status(struct dp_catalog *dp_catalog) { struct dp_catalog_private *catalog = container_of(dp_catalog, struct dp_catalog_private, dp_catalog);

•   int isr = 0;
  

•   int isr, mask;
  
    isr = dp_read_aux(catalog, REG_DP_DP_HPD_INT_STATUS);
    dp_write_aux(catalog, REG_DP_DP_HPD_INT_ACK,
                             (isr & DP_DP_HPD_INT_MASK));
  

•   mask = dp_read_aux(catalog, REG_DP_DP_HPD_INT_MASK);
  
  

•   return isr;
  

•   /*
  

•    * REG_DP_DP_HPD_INT_STATUS reports the status of all interrupts
  

•    * irrespective of their masked status. The HW interrupt will not be
  

•    * generated if an interrupt is masked. However, the interrupt status
  

•    * bit in the register will still be set. The eDP controller driver
  

•    * masks the plug and unplug interrupts unlike DP controller which
  

•    * unmasks all the interrupts. So, do not report the status of the
  

•    * masked interrupts.
  

•    */
  

•   return isr & (mask | ~DP_DP_HPD_INT_MASK);
  

What's still missing in your comments is why you aren't just doing "return isr & mask;". In other words, why is the API for HPD bits different from the API for non-HPD bits? What code out there wants to know about non-HPD interrupts even if they are masked?

Actually, thinking about this more, my preference would be this:

a) Rename the existing function to dp_catalog_hpd_get_intr_status_raw()

b) Create a new function called dp_catalog_hpd_get_intr_status() whose implementation is:

return dp_catalog_hpd_get_intr_status_raw() & mask;

Then any callers who care about the raw status can be changed to call dp_catalog_hpd_get_intr_status_raw(). If no callers need dp_catalog_hpd_get_intr_status_raw() then you don't actually need to create this function.

If you make that change then all of a sudden the API isn't weird/wonky and you can just get rid of the comment I asked you to add.

-Doug