This is a note to let you know that I've just added the patch titled

drm/tilcdc: Precalculate total frametime in tilcdc_crtc_set_mode()

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: drm-tilcdc-precalculate-total-frametime-in-tilcdc_crtc_set_mode.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From ce99f7206c9105851d97202ed08c058af6f11ac4 Mon Sep 17 00:00:00 2001

From: Jyri Sarha jsarha@ti.com Date: Thu, 12 Oct 2017 12:19:46 +0300 Subject: drm/tilcdc: Precalculate total frametime in tilcdc_crtc_set_mode()

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)

Patches currently in stable-queue which might be from jsarha@ti.com are

queue-4.14/drm-tilcdc-precalculate-total-frametime-in-tilcdc_crtc_set_mode.patch