[Freedreno] [PATCH v2 2/3] drm: msm: a6xx: Add support for A618

[John Stultz]

On Wed, Jan 22, 2020 at 11:19 PM Sharat Masetty <smasetty at codeaurora.org> wrote:
>
> This patch adds support for enabling Graphics Bus Interface(GBIF)
> used in multiple A6xx series chipets. Also makes changes to the
> PDC/RSC sequencing specifically required for A618. This is needed
> for proper interfacing with RPMH.
>
> Signed-off-by: Sharat Masetty <smasetty at codeaurora.org>
> ---
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index dc8ec2c..2ac9a51 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -378,6 +378,18 @@ static int a6xx_hw_init(struct msm_gpu *gpu)
>         struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
>         int ret;
>
> +       /*
> +        * During a previous slumber, GBIF halt is asserted to ensure
> +        * no further transaction can go through GPU before GPU
> +        * headswitch is turned off.
> +        *
> +        * This halt is deasserted once headswitch goes off but
> +        * incase headswitch doesn't goes off clear GBIF halt
> +        * here to ensure GPU wake-up doesn't fail because of
> +        * halted GPU transactions.
> +        */
> +       gpu_write(gpu, REG_A6XX_GBIF_HALT, 0x0);
> +
>         /* Make sure the GMU keeps the GPU on while we set it up */
>         a6xx_gmu_set_oob(&a6xx_gpu->gmu, GMU_OOB_GPU_SET);
>

So I already brought this up on #freedreno but figured I'd follow up
on the list.

With linus/master, I'm seeing hard crashes (into usb crash mode) with
the db845c, which I isolated down to this patch, and then to the chunk
above.

Dropping the gpu_write line above gets things booting again for me.

Let me know if there are any follow on patches I can help validate.

thanks
-john