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    Subject[PATCH 4.14 73/95] drm/tilcdc: Precalculate total frametime in tilcdc_crtc_set_mode()
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Jyri Sarha <jsarha@ti.com>

    commit ce99f7206c9105851d97202ed08c058af6f11ac4 upstream.

    We need the total frame refresh time to check if we are too close to
    vertical sync when updating the two framebuffer DMA registers and risk
    a collision. This new method is more accurate that the previous that
    based on mode's vrefresh value, which itself is inaccurate or may not
    even be initialized.

    Reported-by: Kevin Hao <kexin.hao@windriver.com>
    Fixes: 11abbc9f39e0 ("drm/tilcdc: Set framebuffer DMA address to HW only if CRTC is enabled")
    Signed-off-by: Jyri Sarha <jsarha@ti.com>
    Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 13 ++++++++++++-
    1 file changed, 12 insertions(+), 1 deletion(-)

    --- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
    +++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
    @@ -24,6 +24,7 @@
    #include <linux/completion.h>
    #include <linux/dma-mapping.h>
    #include <linux/of_graph.h>
    +#include <linux/math64.h>

    #include "tilcdc_drv.h"
    #include "tilcdc_regs.h"
    @@ -48,6 +49,7 @@ struct tilcdc_crtc {
    unsigned int lcd_fck_rate;

    ktime_t last_vblank;
    + unsigned int hvtotal_us;

    struct drm_framebuffer *curr_fb;
    struct drm_framebuffer *next_fb;
    @@ -292,6 +294,12 @@ static void tilcdc_crtc_set_clk(struct d
    LCDC_V2_CORE_CLK_EN);
    }

    +uint tilcdc_mode_hvtotal(const struct drm_display_mode *mode)
    +{
    + return (uint) div_u64(1000llu * mode->htotal * mode->vtotal,
    + mode->clock);
    +}
    +
    static void tilcdc_crtc_set_mode(struct drm_crtc *crtc)
    {
    struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
    @@ -459,6 +467,9 @@ static void tilcdc_crtc_set_mode(struct
    drm_framebuffer_reference(fb);

    crtc->hwmode = crtc->state->adjusted_mode;
    +
    + tilcdc_crtc->hvtotal_us =
    + tilcdc_mode_hvtotal(&crtc->hwmode);
    }

    static void tilcdc_crtc_enable(struct drm_crtc *crtc)
    @@ -648,7 +659,7 @@ int tilcdc_crtc_update_fb(struct drm_crt
    spin_lock_irqsave(&tilcdc_crtc->irq_lock, flags);

    next_vblank = ktime_add_us(tilcdc_crtc->last_vblank,
    - 1000000 / crtc->hwmode.vrefresh);
    + tilcdc_crtc->hvtotal_us);
    tdiff = ktime_to_us(ktime_sub(next_vblank, ktime_get()));

    if (tdiff < TILCDC_VBLANK_SAFETY_THRESHOLD_US)

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