Re: [Intel-gfx] [PATCH v2 4/5] drm/i915: dont retry stream management at seq_num_m roll over

Sean Paul
2020-02-18T15:41:00Z

On Wed, Feb 12, 2020 at 03:59:41PM +0530, Ramalingam C wrote:
> When roll over detected for seq_num_m, we shouldn't continue with stream
> management with rolled over value.
>
> So we are terminating the stream management retry, on roll over of the
> seq_num_m.
>
> v2:
> using drm_dbg_kms instead of DRM_DEBUG_KMS [Anshuman]
> v3:
> dev_priv is used as i915 [JaniN]
>
> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_hdcp.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
> index b24d12efae0a..b35f50d4a0e9 100644
> --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
> @@ -1419,11 +1419,6 @@ int _hdcp2_propagate_stream_management_info(struct intel_connector *connector)
>
> err_exit:
> hdcp->seq_num_m++;
> - if (hdcp->seq_num_m > HDCP_2_2_SEQ_NUM_MAX) {
> - DRM_DEBUG_KMS("seq_num_m roll over.\n");
> - ret = -1;
> - }
> -
> return ret;
> }
>
> @@ -1618,8 +1613,11 @@ hdcp2_propagate_stream_management_info(struct intel_connector *connector)
>
> for (i = 0; i < tries; i++) {
> ret = _hdcp2_propagate_stream_management_info(connector);
> - if (!ret)
> + if (!ret || connector->hdcp.seq_num_m > HDCP_2_2_SEQ_NUM_MAX) {
> + if (connector->hdcp.seq_num_m > HDCP_2_2_SEQ_NUM_MAX)
> + drm_dbg_kms(&i915->drm, "seq_num_m roll over.\n");
> break;
> + }

IMO it doesn't read quite right bunching up a success outcome and a failure,
and it's actually less code (character-wise) to do:

if (connector->hdcp.seq_num_m > HDCP_2_2_SEQ_NUM_MAX) {
drm_dbg_kms(&i915->drm, "seq_num_m roll over.\n");
break;
} else if (!ret) {
break;
}

feel free to add

Reviewed-by: Sean Paul <sean@poorly.run>

with this addressed

>
> drm_dbg_kms(&i915->drm,
> "HDCP2 stream management %d of %d Failed.(%d)\n",
> --
> 2.20.1
>
> _______________________________________________
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> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

--
Sean Paul, Software Engineer, Google / Chromium OS