Re: [PATCH 6/6] drm/exynos: do not copy adjusted mode into mode during crtc mode_set

[Joonyoung Shim <jy0922.shim@samsung.com>]

Hi,

On 01/23/2015 09:43 PM, Gustavo Padovan wrote:
> From: Daniel Kurtz <djkurtz@chromium.org>
> 
> The 'mode' is the modeline information which specifies the ideal mode
> requested by the mode set initiator (usually userspace).
> The 'adjusted_mode' is the actual hardware mode after all the crtcs
> and encoders have had a chance to "fix it up".
> 
> The adjusted_mode starts as a duplicate of the mode in
> drm_crtc_helper_set_mode(), and gets modified as required.  There is no
> reason to touch the original requested mode.
> 

Agree, but is there any side effect after this commit? Should we save
adjusted_mode to other variable and use it?

Thanks.

> In fact, doing so will cause us to think a new mode is being requested
> whenever userspace tries to establish a new framebuffer with
> drmModeSetCrtc(), since userspace will still be using the ideal mode, but
> the crtc will be incorrectly comparing it against the adjusted_mode.
> 
> Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_crtc.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> index 5cd6c1a..7fd6426 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> @@ -91,12 +91,6 @@ exynos_drm_crtc_mode_set(struct drm_crtc *crtc, struct drm_display_mode *mode,
>  	unsigned int crtc_h;
>  	int ret;
>  
> -	/*
> -	 * copy the mode data adjusted by mode_fixup() into crtc->mode
> -	 * so that hardware can be seet to proper mode.
> -	 */
> -	memcpy(&crtc->mode, adjusted_mode, sizeof(*adjusted_mode));
> -
>  	ret = exynos_check_plane(crtc->primary, fb);
>  	if (ret < 0)
>  		return ret;
> 

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