Re: [PATCH v6 4/8] drm/msm/dp: avoid handling masked interrupts

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On 31/03/2022 08:53, Sankeerth Billakanti (QUIC) wrote:
Hi Dmitry,

On Wed, 30 Mar 2022 at 19:03, Sankeerth Billakanti
<quic_sbillaka@xxxxxxxxxxx> wrote:

The interrupt register will still reflect the connect and disconnect
interrupt status without generating an actual HW interrupt.
The controller driver should not handle those masked interrupts.

Signed-off-by: Sankeerth Billakanti <quic_sbillaka@xxxxxxxxxxx>
---
  drivers/gpu/drm/msm/dp/dp_catalog.c | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.c
b/drivers/gpu/drm/msm/dp/dp_catalog.c
index 3c16f95..1809ce2 100644
--- a/drivers/gpu/drm/msm/dp/dp_catalog.c
+++ b/drivers/gpu/drm/msm/dp/dp_catalog.c
@@ -608,13 +608,14 @@ 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;
+       return isr & (DP_DP_HPD_STATE_STATUS_MASK | mask);

I suspect that the logic is inverted here. Shouldn't it be:

return isr & DP_DP_HPD_STATE_STATUS_MASK & mask;

?

The value of DP_DP_HPD_STATE_STATUS_MASK is 0xE0000000 and the value of the read
interrupt mask variable could be is 0xF.

The mask value is indicated via the register, REG_DP_DP_HPD_INT_MASK, bits 3:0.
The HPD status is indicated via a different read-only register REG_DP_DP_HPD_INT_STATUS, bits 31:29.

I see. Maybe the following expression would be better?

return isr & (mask & ~DP_DP_HPD_INT_MASK);


isr & DP_DP_HPD_STATE_STATUS_MASK & mask, will return 0 always.

  }

  int dp_catalog_ctrl_get_interrupt(struct dp_catalog *dp_catalog)
--
2.7.4



--
With best wishes
Dmitry

Thank you,
Sankeerth


--
With best wishes
Dmitry



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