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SubjectRe: [PATCH v4 2/5] drm/mxsfb: Fix initial corrupt frame when activating display
On 08.08.2018 18:08, Leonard Crestez wrote:
> LCDIF will repeatedly display data from CUR_BUF and set CUR_BUF to
> NEXT_BUF when done. Since we are only ever writing to NEXT_BUF the
> display will show an initial corrupt frame.
>
> Fix by writing the FB paddr to both CUR_BUF and NEXT_BUF when
> activating the CRTC.
>
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> Tested-by: Philipp Zabel <p.zabel@pengutronix.de>

Reviewed-by: Stefan Agner <stefan@agner.ch>

> ---
> drivers/gpu/drm/mxsfb/mxsfb_crtc.c | 45 +++++++++++++++++++++---------
> 1 file changed, 32 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> index e4fcbb65b969..24b1f0c1432e 100644
> --- a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> +++ b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> @@ -191,10 +191,25 @@ static int mxsfb_reset_block(void __iomem *reset_addr)
> return ret;
>
> return clear_poll_bit(reset_addr, MODULE_CLKGATE);
> }
>
> +static dma_addr_t mxsfb_get_fb_paddr(struct mxsfb_drm_private *mxsfb)
> +{
> + struct drm_framebuffer *fb = mxsfb->pipe.plane.state->fb;
> + struct drm_gem_cma_object *gem;
> +
> + if (!fb)
> + return 0;
> +
> + gem = drm_fb_cma_get_gem_obj(fb, 0);
> + if (!gem)
> + return 0;
> +
> + return gem->paddr;
> +}
> +
> static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb)
> {
> struct drm_display_mode *m = &mxsfb->pipe.crtc.state->adjusted_mode;
> const u32 bus_flags = mxsfb->connector.display_info.bus_flags;
> u32 vdctrl0, vsync_pulse_len, hsync_pulse_len;
> @@ -267,12 +282,22 @@ static void mxsfb_crtc_mode_set_nofb(struct
> mxsfb_drm_private *mxsfb)
> mxsfb->base + LCDC_VDCTRL4);
> }
>
> void mxsfb_crtc_enable(struct mxsfb_drm_private *mxsfb)
> {
> + dma_addr_t paddr;
> +
> mxsfb_enable_axi_clk(mxsfb);
> mxsfb_crtc_mode_set_nofb(mxsfb);
> +
> + /* Write cur_buf as well to avoid an initial corrupt frame */
> + paddr = mxsfb_get_fb_paddr(mxsfb);
> + if (paddr) {
> + writel(paddr, mxsfb->base + mxsfb->devdata->cur_buf);
> + writel(paddr, mxsfb->base + mxsfb->devdata->next_buf);
> + }
> +
> mxsfb_enable_controller(mxsfb);
> }
>
> void mxsfb_crtc_disable(struct mxsfb_drm_private *mxsfb)
> {
> @@ -283,16 +308,12 @@ void mxsfb_crtc_disable(struct mxsfb_drm_private *mxsfb)
> void mxsfb_plane_atomic_update(struct mxsfb_drm_private *mxsfb,
> struct drm_plane_state *state)
> {
> struct drm_simple_display_pipe *pipe = &mxsfb->pipe;
> struct drm_crtc *crtc = &pipe->crtc;
> - struct drm_framebuffer *fb = pipe->plane.state->fb;
> struct drm_pending_vblank_event *event;
> - struct drm_gem_cma_object *gem;
> -
> - if (!crtc)
> - return;
> + dma_addr_t paddr;
>
> spin_lock_irq(&crtc->dev->event_lock);
> event = crtc->state->event;
> if (event) {
> crtc->state->event = NULL;
> @@ -303,14 +324,12 @@ void mxsfb_plane_atomic_update(struct
> mxsfb_drm_private *mxsfb,
> drm_crtc_send_vblank_event(crtc, event);
> }
> }
> spin_unlock_irq(&crtc->dev->event_lock);
>
> - if (!fb)
> - return;
> -
> - gem = drm_fb_cma_get_gem_obj(fb, 0);
> -
> - mxsfb_enable_axi_clk(mxsfb);
> - writel(gem->paddr, mxsfb->base + mxsfb->devdata->next_buf);
> - mxsfb_disable_axi_clk(mxsfb);
> + paddr = mxsfb_get_fb_paddr(mxsfb);
> + if (paddr) {
> + mxsfb_enable_axi_clk(mxsfb);
> + writel(paddr, mxsfb->base + mxsfb->devdata->next_buf);
> + mxsfb_disable_axi_clk(mxsfb);
> + }
> }

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