On 2014ë
12ì 11ì¼ 01:57, Gustavo Padovan wrote:
> From: Daniel Kurtz <djkurtz at chromium.org>
>
> A framebuffer gets committed to FIMD's default window like this:
> exynos_drm_crtc_update()
> exynos_plane_commit()
> fimd_win_commit()
>
> fimd_win_commit() programs BUF_START[0]. At each vblank, FIMD hardware
> copies the value from BUF_START to BUF_START_S (BUF_START's shadow
> register), starts scanning out from BUF_START_S, and asserts its irq.
>
> This irq is handled by fimd_irq_handler(), which calls
> exynos_drm_crtc_finish_pageflip() to free the old buffer that FIMD just
> finished scanning out, and potentially commit the next pending flip.
>
> There is a race, however, if fimd_win_commit() programs BUF_START(0)
> between the actual vblank irq, and its corresponding fimd_irq_handler().
>
> => FIMD vblank: BUF_START_S[0] := BUF_START[0], and irq asserted
> | => fimd_win_commit(0) writes new BUF_START[0]
> | exynos_drm_crtc_try_do_flip() marks exynos_fb as prepared
> => fimd_irq_handler()
> exynos_drm_crtc_finish_pageflip() sees prepared exynos_fb,
> and unmaps "old" fb
> ==> but, since BUF_START_S[0] still points to that "old" fb...
> ==> FIMD iommu fault
>
> This patch ensures that fimd_irq_handler() only calls
> exynos_drm_crtc_finish_pageflip() if any previously scheduled flip
> has really completed.
>
> This works because exynos_drm_crtc's flip fifo ensures that
> fimd_win_commit() is never called more than once per
> exynos_drm_crtc_finish_pageflip().
>
> Signed-off-by: Daniel Kurtz <djkurtz at chromium.org>
> Reviewed-by: Sean Paul <seanpaul at chromium.org>
> Signed-off-by: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
> ---
> drivers/gpu/drm/exynos/exynos_drm_fimd.c | 31 ++++++++++++++++++++++++-------
> include/video/samsung_fimd.h | 1 +
> 2 files changed, 25 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> index e5810d1..95bac27 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c
> @@ -55,6 +55,7 @@
> #define VIDOSD_D(win) (VIDOSD_BASE + 0x0C + (win) * 16)
>
> #define VIDWx_BUF_START(win, buf) (VIDW_BUF_START(buf) + (win) * 8)
> +#define VIDWx_BUF_START_S(win, buf) (VIDW_BUF_START_S(buf) + (win) * 8)
> #define VIDWx_BUF_END(win, buf) (VIDW_BUF_END(buf) + (win) * 8)
> #define VIDWx_BUF_SIZE(win, buf) (VIDW_BUF_SIZE(buf) + (win) * 4)
>
> @@ -1039,6 +1040,7 @@ static irqreturn_t fimd_irq_handler(int irq, void
> *dev_id)
> {
> struct fimd_context *ctx = (struct fimd_context *)dev_id;
> u32 val, clear_bit;
> + u32 start, start_s;
>
> val = readl(ctx->regs + VIDINTCON1);
>
> @@ -1051,19 +1053,34 @@ static irqreturn_t fimd_irq_handler(int irq, void
> *dev_id)
> goto out;
>
> if (ctx->i80_if) {
> - exynos_drm_crtc_finish_pageflip(ctx->drm_dev, ctx->pipe);
> -
> /* Exits triggering mode */
> atomic_set(&ctx->triggering, 0);
> } else {
> drm_handle_vblank(ctx->drm_dev, ctx->pipe);
> + }
> +
> + /*
> + * Ensure finish_pageflip is called iff a pending flip has completed.
> + * This works around a race between a page_flip request and the latency
> + * between vblank interrupt and this irq_handler:
> + * => FIMD vblank: BUF_START_S[0] := BUF_START[0], and asserts irq
> + * | => fimd_win_commit(0) writes new BUF_START[0]
> + * | exynos_drm_crtc_try_do_flip() marks exynos_fb as prepared
> + * => fimd_irq_handler()
> + * exynos_drm_crtc_finish_pageflip() sees prepared exynos_fb,
> + * and unmaps "old" fb
> + * ==> but, since BUF_START_S[0] still points to that "old" fb...
> + * ==> FIMD iommu fault
> + */
> + start = readl(ctx->regs + VIDWx_BUF_START(0, 0));
> + start_s = readl(ctx->regs + VIDWx_BUF_START_S(0, 0));
> + if (start == start_s)
> exynos_drm_crtc_finish_pageflip(ctx->drm_dev, ctx->pipe);
Did you test abvoe codes on I80 mode? If not so, I think this function
should be called only in case of RGB mode until checked.
>
> - /* set wait vsync event to zero and wake up queue. */
> - if (atomic_read(&ctx->wait_vsync_event)) {
> - atomic_set(&ctx->wait_vsync_event, 0);
> - wake_up(&ctx->wait_vsync_queue);
> - }
> + /* set wait vsync event to zero and wake up queue. */
> + if (atomic_read(&ctx->wait_vsync_event)) {
> + atomic_set(&ctx->wait_vsync_event, 0);
> + wake_up(&ctx->wait_vsync_queue);
And in case of i80 mode, wait_vsync_queue will be waked up by
fimd_te_handler so I think above relevant codes should be called only in
case of RGB mode.
Thanks,
Inki Dae
> }
>
> out:
> diff --git a/include/video/samsung_fimd.h b/include/video/samsung_fimd.h
> index a20e4a3..f81d081 100644
> --- a/include/video/samsung_fimd.h
> +++ b/include/video/samsung_fimd.h
> @@ -291,6 +291,7 @@
>
> /* Video buffer addresses */
> #define VIDW_BUF_START(_buff) (0xA0 + ((_buff) * 8))
> +#define VIDW_BUF_START_S(_buff) (0x40A0 + ((_buff) * 8))
> #define VIDW_BUF_START1(_buff) (0xA4 + ((_buff) * 8))
> #define VIDW_BUF_END(_buff) (0xD0 + ((_buff) * 8))
> #define VIDW_BUF_END1(_buff) (0xD4 + ((_buff) * 8))
>
