[PATCH] drm/etnaviv: disable MLCG and pulse eater on GPU reset

[Christian Gmeiner]

>
> Module level clock gating and the pulse eater might interfere with
> the GPU reset, as they both have the potential to stop the clock
> and thus reset propagation to parts of the GPU.
>
> Signed-off-by: Lucas Stach <l.stach at pengutronix.de>

Reviewed-by: Christian Gmeiner <cgmeiner at igalia.com>

> ---
> I'm not aware of any cases where this would have been an issue, but
> it is what the downstream driver does and fundametally seems like
> the right thing to do.
> ---
>  drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> index de8c9894967c..41aab1aa330b 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> @@ -505,8 +505,19 @@ static int etnaviv_hw_reset(struct etnaviv_gpu *gpu)
>         timeout = jiffies + msecs_to_jiffies(1000);
>
>         while (time_is_after_jiffies(timeout)) {
> -               /* enable clock */
>                 unsigned int fscale = 1 << (6 - gpu->freq_scale);
> +               u32 pulse_eater = 0x01590880;
> +
> +               /* disable clock gating */
> +               gpu_write_power(gpu, VIVS_PM_POWER_CONTROLS, 0x0);
> +
> +               /* disable pulse eater */
> +               pulse_eater |= BIT(17);
> +               gpu_write_power(gpu, VIVS_PM_PULSE_EATER, pulse_eater);
> +               pulse_eater |= BIT(0);
> +               gpu_write_power(gpu, VIVS_PM_PULSE_EATER, pulse_eater);
> +
> +               /* enable clock */
>                 control = VIVS_HI_CLOCK_CONTROL_FSCALE_VAL(fscale);
>                 etnaviv_gpu_load_clock(gpu, control);
>
> --
> 2.39.2
>


-- 
greets
--
Christian Gmeiner, MSc

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