Re: [RFC PATCH 02/14] drm/exynos: dsi: delay setting clocks after reset

[Andrzej Hajda <a.hajda@samsung.com>]

Hi YoungJun,

Thanks for the whole patchset.

On 04/15/2014 07:47 AM, YoungJun Cho wrote:
> Some phy control registers are not kept after software reset.
> So this patch makes the clocks containing phy control to be set
> after software reset.
>
> Signed-off-by: YoungJun Cho <yj44.cho@samsung.com>
> Signed-off-by: Inki Dae <inki.dae@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_dsi.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index 956e5f3..2cf1f0b 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -946,10 +946,10 @@ static irqreturn_t exynos_dsi_irq(int irq, void *dev_id)
>  
>  static int exynos_dsi_init(struct exynos_dsi *dsi)
>  {
> -	exynos_dsi_enable_clock(dsi);
>  	exynos_dsi_reset(dsi);
>  	enable_irq(dsi->irq);
>  	exynos_dsi_wait_for_reset(dsi);
> +	exynos_dsi_enable_clock(dsi);
>  	exynos_dsi_init_link(dsi);
>  
>  	return 0;
Are you sure this sequence is OK? I have observed that sequence:

dsi power off
dsi power on
dsi_reset

on 4210 or 4412 resulted in lack of irq after reset, only enabling
clocks helped.
And according to documentation reset do not touch registers set by
exynos_dsi_enable_clock,
so the current solution should work.

Regards
Andrzej