[RFC][PATCH 1/2] drm/radeon: remove unneeded HDMI r/w ops on DCE4+

[Alex Deucher]

On Sun, Oct 6, 2013 at 4:46 PM, Rafał Miłecki <zajec5 at gmail.com> wrote:
> Write to HDMI_VBI_PACKET_CONTROL was duplicated.
> Writes to AFMT_AUDIO_CRC_CONTROL and AFMT_RAMP_CONTROL[0-3] came from
> DCE2/3 code (copy & paste) and were never needed on DCE4+.
>
> See https://bugzilla.kernel.org/show_bug.cgi?id=62591 for details.

I think in general it would be better to do a read/modify/write
sequences for all hdmi register updates rather than just writing.
That's generally what the hw team recommends and what the catalyst
driver does.

Alex

> ---
> That patches weren't tested with the HW, please don't apply them yet.
> ---
>  drivers/gpu/drm/radeon/evergreen_hdmi.c |   11 -----------
>  1 file changed, 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/evergreen_hdmi.c b/drivers/gpu/drm/radeon/evergreen_hdmi.c
> index f71ce39..50f6299 100644
> --- a/drivers/gpu/drm/radeon/evergreen_hdmi.c
> +++ b/drivers/gpu/drm/radeon/evergreen_hdmi.c
> @@ -257,11 +257,6 @@ void evergreen_hdmi_setmode(struct drm_encoder *encoder, struct drm_display_mode
>         evergreen_audio_set_dto(encoder, mode->clock);
>
>         WREG32(HDMI_VBI_PACKET_CONTROL + offset,
> -              HDMI_NULL_SEND); /* send null packets when required */
> -
> -       WREG32(AFMT_AUDIO_CRC_CONTROL + offset, 0x1000);
> -
> -       WREG32(HDMI_VBI_PACKET_CONTROL + offset,
>                HDMI_NULL_SEND | /* send null packets when required */
>                HDMI_GC_SEND | /* send general control packets */
>                HDMI_GC_CONT); /* send general control packets every frame */
> @@ -349,12 +344,6 @@ void evergreen_hdmi_setmode(struct drm_encoder *encoder, struct drm_display_mode
>
>         WREG32_OR(AFMT_AUDIO_PACKET_CONTROL + offset,
>                   AFMT_AUDIO_SAMPLE_SEND); /* send audio packets */
> -
> -       /* it's unknown what these bits do excatly, but it's indeed quite useful for debugging */
> -       WREG32(AFMT_RAMP_CONTROL0 + offset, 0x00FFFFFF);
> -       WREG32(AFMT_RAMP_CONTROL1 + offset, 0x007FFFFF);
> -       WREG32(AFMT_RAMP_CONTROL2 + offset, 0x00000001);
> -       WREG32(AFMT_RAMP_CONTROL3 + offset, 0x00000001);
>  }
>
>  void evergreen_hdmi_enable(struct drm_encoder *encoder, bool enable)
> --
> 1.7.10.4
>