Re: [PATCHv2 45/45] drm: omapdrm: add lock for fb pinning

Hi Tomi,

Thank you for the patch.

On Thursday 04 June 2015 12:03:02 Tomi Valkeinen wrote:

Before atomic modesetting omap_framebuffer_pin() and omap_framebuffer_unpin() were always called with modesetting locks taken. With atomic modesetting support this is no longer the case, and we need locking to protect the pin_count and the paddr, as multiple threads may pin the same fb concurrently.

This patch adds a mutex to struct omap_framebuffer, and uses it in omap_framebuffer_pin() and omap_framebuffer_unpin().

Signed-off-by: Tomi Valkeinen tomi.valkeinen@ti.com

Acked-by: Laurent Pinchart laurent.pinchart@ideasonboard.com

---

drivers/gpu/drm/omapdrm/omap_fb.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/omapdrm/omap_fb.c b/drivers/gpu/drm/omapdrm/omap_fb.c index e505140a8782..0b967e76df1a 100644 --- a/drivers/gpu/drm/omapdrm/omap_fb.c +++ b/drivers/gpu/drm/omapdrm/omap_fb.c @@ -89,6 +89,8 @@ struct omap_framebuffer { int pin_count; const struct format *format; struct plane planes[4];

• /* lock for pinning (pin_count and planes.paddr) */
• struct mutex lock;

};

static int omap_framebuffer_create_handle(struct drm_framebuffer *fb, @@ -250,8 +252,11 @@ int omap_framebuffer_pin(struct drm_framebuffer *fb) struct omap_framebuffer *omap_fb = to_omap_framebuffer(fb); int ret, i, n = drm_format_num_planes(fb->pixel_format);

• mutex_lock(&omap_fb->lock);
• if (omap_fb->pin_count > 0) { omap_fb->pin_count++;

• mutex_unlock(&omap_fb->lock);
  

  return 0; }

@@ -265,6 +270,8 @@ int omap_framebuffer_pin(struct drm_framebuffer *fb)

omap_fb->pin_count++;

• mutex_unlock(&omap_fb->lock);
• return 0;

fail: @@ -274,6 +281,8 @@ fail: plane->paddr = 0; }

• mutex_unlock(&omap_fb->lock);
• return ret;

}

@@ -283,10 +292,14 @@ int omap_framebuffer_unpin(struct drm_framebuffer *fb) struct omap_framebuffer *omap_fb = to_omap_framebuffer(fb); int ret, i, n = drm_format_num_planes(fb->pixel_format);

• mutex_lock(&omap_fb->lock);
• omap_fb->pin_count--;

• if (omap_fb->pin_count > 0)

• if (omap_fb->pin_count > 0) {

• mutex_unlock(&omap_fb->lock);
  

  return 0;

• }

  for (i = 0; i < n; i++) { struct plane *plane = &omap_fb->planes[i];

@@ -296,9 +309,12 @@ int omap_framebuffer_unpin(struct drm_framebuffer *fb) plane->paddr = 0; }

• mutex_unlock(&omap_fb->lock);
• return 0;

fail:

• mutex_unlock(&omap_fb->lock); return ret;

}

@@ -411,6 +427,7 @@ struct drm_framebuffer *omap_framebuffer_init(struct drm_device *dev,

fb = &omap_fb->base; omap_fb->format = format;

• mutex_init(&omap_fb->lock);

  for (i = 0; i < n; i++) { struct plane *plane = &omap_fb->planes[i];