diff mbox

[3/3] drm/msm: hijack firmware fb's memory

Message ID 20170711133822.31978-4-robdclark@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Rob Clark July 11, 2017, 1:38 p.m. UTC
If we are kicking out efifb or simplefb then we want to hijack the
outgoing fb's memory and wrap it in a gem object so that it can
be allocated for use by fbdev helpers.  This way we keep the same
scanout buffer that the display is already using.

This is prep-work for enabling drm/msm to take over a display that
is enabled already by the bootloader.

Signed-off-by: Rob Clark <robdclark@gmail.com>
---
 drivers/gpu/drm/msm/msm_drv.c | 82 +++++++++++++++++++++++++++++++++----------
 1 file changed, 64 insertions(+), 18 deletions(-)

Comments

Daniel Vetter July 11, 2017, 2:03 p.m. UTC | #1
On Tue, Jul 11, 2017 at 3:38 PM, Rob Clark <robdclark@gmail.com> wrote:
> +static unsigned long hijack_firmware_fb(struct drm_device *dev)
> +{
> +       struct msm_drm_private *priv = dev->dev_private;
> +       unsigned long size;
> +       int i;
> +
> +       /* if we have simplefb/efifb, find it's aperture and hijack
> +        * that before we kick out the firmware fb's.
> +        *
> +        * TODO we probably should hold registration_lock
> +        */
> +       for (i = 0; i < FB_MAX; i++) {
> +               struct fb_info *fb = get_fb_info(i);
> +
> +               if (IS_ERR_OR_NULL(fb))
> +                       continue;
> +
> +               if (!fb->apertures->count)
> +                       continue;
> +
> +               /* if we find efifb or simplefb, we are about to
> +                * kick them out, so hijack their memory:
> +                */
> +               if ((strcmp(fb->fix.id, "EFI VGA") == 0) ||
> +                               (strcmp(fb->fix.id, "simple") == 0)) {
> +
> +                       priv->vram.paddr = fb->apertures->ranges[0].base;
> +                       size = fb->apertures->ranges[0].size;
> +               }
> +
> +               put_fb_info(fb);
> +
> +               if (size)
> +                       return size;
> +       }
> +
> +       return 0;
> +}

I think this should be a helper function in at least drm_fb_helper.c,
which would then fill in both base&size in a passed-in struct. But
yeah this seems a lot better than the old one.

In the future we could then also extend this with kicking out other
firmware fb things.
-Daniel
Chris Wilson July 11, 2017, 2:17 p.m. UTC | #2
Quoting Rob Clark (2017-07-11 14:38:22)
> +static unsigned long hijack_firmware_fb(struct drm_device *dev)
> +{
> +       struct msm_drm_private *priv = dev->dev_private;
> +       unsigned long size;
> +       int i;
> +
> +       /* if we have simplefb/efifb, find it's aperture and hijack
> +        * that before we kick out the firmware fb's.
> +        *
> +        * TODO we probably should hold registration_lock
> +        */
> +       for (i = 0; i < FB_MAX; i++) {
> +               struct fb_info *fb = get_fb_info(i);
> +
> +               if (IS_ERR_OR_NULL(fb))
> +                       continue;
> +
> +               if (!fb->apertures->count)

Does get_fb_info() not return a reference if its apertures->count==0?

> +                       continue;
> +
> +               /* if we find efifb or simplefb, we are about to
> +                * kick them out, so hijack their memory:
> +                */
> +               if ((strcmp(fb->fix.id, "EFI VGA") == 0) ||
> +                               (strcmp(fb->fix.id, "simple") == 0)) {
> +
> +                       priv->vram.paddr = fb->apertures->ranges[0].base;
> +                       size = fb->apertures->ranges[0].size;
> +               }
> +
> +               put_fb_info(fb);
> +
> +               if (size)
> +                       return size;

size is never initialised to 0. Perhaps just return the reference to the
matching fb? Hopefully sidestepping a few of the worries about it
disappearing during the probe.
-Chris
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Rob Clark July 11, 2017, 2:31 p.m. UTC | #3
On Tue, Jul 11, 2017 at 10:03 AM, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Tue, Jul 11, 2017 at 3:38 PM, Rob Clark <robdclark@gmail.com> wrote:
>> +static unsigned long hijack_firmware_fb(struct drm_device *dev)
>> +{
>> +       struct msm_drm_private *priv = dev->dev_private;
>> +       unsigned long size;
>> +       int i;
>> +
>> +       /* if we have simplefb/efifb, find it's aperture and hijack
>> +        * that before we kick out the firmware fb's.
>> +        *
>> +        * TODO we probably should hold registration_lock
>> +        */
>> +       for (i = 0; i < FB_MAX; i++) {
>> +               struct fb_info *fb = get_fb_info(i);
>> +
>> +               if (IS_ERR_OR_NULL(fb))
>> +                       continue;
>> +
>> +               if (!fb->apertures->count)
>> +                       continue;
>> +
>> +               /* if we find efifb or simplefb, we are about to
>> +                * kick them out, so hijack their memory:
>> +                */
>> +               if ((strcmp(fb->fix.id, "EFI VGA") == 0) ||
>> +                               (strcmp(fb->fix.id, "simple") == 0)) {
>> +
>> +                       priv->vram.paddr = fb->apertures->ranges[0].base;
>> +                       size = fb->apertures->ranges[0].size;
>> +               }
>> +
>> +               put_fb_info(fb);
>> +
>> +               if (size)
>> +                       return size;
>> +       }
>> +
>> +       return 0;
>> +}
>
> I think this should be a helper function in at least drm_fb_helper.c,
> which would then fill in both base&size in a passed-in struct. But
> yeah this seems a lot better than the old one.

Yeah, I guess we could do that.. but probably not in drm_fb_helper.c
since that is compile-time optional.  Better suggestions about where
it should live?  If you have fbdev but not DRM_FBDEV_EMULATION you
still want to do this, I think.  Otherwise we can't completely take
over the display setup by firmware (ie. no way to create
plane->state->fb).

BR,
-R


> In the future we could then also extend this with kicking out other
> firmware fb things.
> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
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Rob Clark July 11, 2017, 2:34 p.m. UTC | #4
On Tue, Jul 11, 2017 at 10:17 AM, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> Quoting Rob Clark (2017-07-11 14:38:22)
>> +static unsigned long hijack_firmware_fb(struct drm_device *dev)
>> +{
>> +       struct msm_drm_private *priv = dev->dev_private;
>> +       unsigned long size;
>> +       int i;
>> +
>> +       /* if we have simplefb/efifb, find it's aperture and hijack
>> +        * that before we kick out the firmware fb's.
>> +        *
>> +        * TODO we probably should hold registration_lock
>> +        */
>> +       for (i = 0; i < FB_MAX; i++) {
>> +               struct fb_info *fb = get_fb_info(i);
>> +
>> +               if (IS_ERR_OR_NULL(fb))
>> +                       continue;
>> +
>> +               if (!fb->apertures->count)
>
> Does get_fb_info() not return a reference if its apertures->count==0?

yeah, you are right.. overlooked that when converting from iterating
registered_fb[] table directly without taking a reference..

>> +                       continue;
>> +
>> +               /* if we find efifb or simplefb, we are about to
>> +                * kick them out, so hijack their memory:
>> +                */
>> +               if ((strcmp(fb->fix.id, "EFI VGA") == 0) ||
>> +                               (strcmp(fb->fix.id, "simple") == 0)) {
>> +
>> +                       priv->vram.paddr = fb->apertures->ranges[0].base;
>> +                       size = fb->apertures->ranges[0].size;
>> +               }
>> +
>> +               put_fb_info(fb);
>> +
>> +               if (size)
>> +                       return size;
>
> size is never initialised to 0. Perhaps just return the reference to the
> matching fb? Hopefully sidestepping a few of the worries about it
> disappearing during the probe.

I guess that would be a useful approach if I wanted a single helper
that did both this and kicking out firmware fb's..

BR,
-R
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Daniel Vetter July 11, 2017, 2:42 p.m. UTC | #5
On Tue, Jul 11, 2017 at 4:31 PM, Rob Clark <robdclark@gmail.com> wrote:
> On Tue, Jul 11, 2017 at 10:03 AM, Daniel Vetter <daniel@ffwll.ch> wrote:
>> On Tue, Jul 11, 2017 at 3:38 PM, Rob Clark <robdclark@gmail.com> wrote:
>>> +static unsigned long hijack_firmware_fb(struct drm_device *dev)
>>> +{
>>> +       struct msm_drm_private *priv = dev->dev_private;
>>> +       unsigned long size;
>>> +       int i;
>>> +
>>> +       /* if we have simplefb/efifb, find it's aperture and hijack
>>> +        * that before we kick out the firmware fb's.
>>> +        *
>>> +        * TODO we probably should hold registration_lock
>>> +        */
>>> +       for (i = 0; i < FB_MAX; i++) {
>>> +               struct fb_info *fb = get_fb_info(i);
>>> +
>>> +               if (IS_ERR_OR_NULL(fb))
>>> +                       continue;
>>> +
>>> +               if (!fb->apertures->count)
>>> +                       continue;
>>> +
>>> +               /* if we find efifb or simplefb, we are about to
>>> +                * kick them out, so hijack their memory:
>>> +                */
>>> +               if ((strcmp(fb->fix.id, "EFI VGA") == 0) ||
>>> +                               (strcmp(fb->fix.id, "simple") == 0)) {
>>> +
>>> +                       priv->vram.paddr = fb->apertures->ranges[0].base;
>>> +                       size = fb->apertures->ranges[0].size;
>>> +               }
>>> +
>>> +               put_fb_info(fb);
>>> +
>>> +               if (size)
>>> +                       return size;
>>> +       }
>>> +
>>> +       return 0;
>>> +}
>>
>> I think this should be a helper function in at least drm_fb_helper.c,
>> which would then fill in both base&size in a passed-in struct. But
>> yeah this seems a lot better than the old one.
>
> Yeah, I guess we could do that.. but probably not in drm_fb_helper.c
> since that is compile-time optional.  Better suggestions about where
> it should live?  If you have fbdev but not DRM_FBDEV_EMULATION you
> still want to do this, I think.  Otherwise we can't completely take
> over the display setup by firmware (ie. no way to create
> plane->state->fb).

Hm right, maybe add a drm_fwfb_helper.c or so. If you look at
i915_kick_out_vgacon(), that might be another candidate for that file.
Putting it into fbdev itself seems like a bad idea, because
maintenance pains.
-Daniel
Rob Clark July 11, 2017, 7:53 p.m. UTC | #6
On Tue, Jul 11, 2017 at 10:42 AM, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Tue, Jul 11, 2017 at 4:31 PM, Rob Clark <robdclark@gmail.com> wrote:
>> On Tue, Jul 11, 2017 at 10:03 AM, Daniel Vetter <daniel@ffwll.ch> wrote:
>>> On Tue, Jul 11, 2017 at 3:38 PM, Rob Clark <robdclark@gmail.com> wrote:
>>>> +static unsigned long hijack_firmware_fb(struct drm_device *dev)
>>>> +{
>>>> +       struct msm_drm_private *priv = dev->dev_private;
>>>> +       unsigned long size;
>>>> +       int i;
>>>> +
>>>> +       /* if we have simplefb/efifb, find it's aperture and hijack
>>>> +        * that before we kick out the firmware fb's.
>>>> +        *
>>>> +        * TODO we probably should hold registration_lock
>>>> +        */
>>>> +       for (i = 0; i < FB_MAX; i++) {
>>>> +               struct fb_info *fb = get_fb_info(i);
>>>> +
>>>> +               if (IS_ERR_OR_NULL(fb))
>>>> +                       continue;
>>>> +
>>>> +               if (!fb->apertures->count)
>>>> +                       continue;
>>>> +
>>>> +               /* if we find efifb or simplefb, we are about to
>>>> +                * kick them out, so hijack their memory:
>>>> +                */
>>>> +               if ((strcmp(fb->fix.id, "EFI VGA") == 0) ||
>>>> +                               (strcmp(fb->fix.id, "simple") == 0)) {
>>>> +
>>>> +                       priv->vram.paddr = fb->apertures->ranges[0].base;
>>>> +                       size = fb->apertures->ranges[0].size;
>>>> +               }
>>>> +
>>>> +               put_fb_info(fb);
>>>> +
>>>> +               if (size)
>>>> +                       return size;
>>>> +       }
>>>> +
>>>> +       return 0;
>>>> +}
>>>
>>> I think this should be a helper function in at least drm_fb_helper.c,
>>> which would then fill in both base&size in a passed-in struct. But
>>> yeah this seems a lot better than the old one.
>>
>> Yeah, I guess we could do that.. but probably not in drm_fb_helper.c
>> since that is compile-time optional.  Better suggestions about where
>> it should live?  If you have fbdev but not DRM_FBDEV_EMULATION you
>> still want to do this, I think.  Otherwise we can't completely take
>> over the display setup by firmware (ie. no way to create
>> plane->state->fb).
>
> Hm right, maybe add a drm_fwfb_helper.c or so. If you look at
> i915_kick_out_vgacon(), that might be another candidate for that file.
> Putting it into fbdev itself seems like a bad idea, because
> maintenance pains.

Hmm, would it be weird to have an:

  obj-$(CONFIG_FB) += drm_fbfw_helper.o

in drm/Makefile?  Or is there a better way to do that?

I'm also wondering a bit about the CONFIG_FB=n case.. you might still
have CONFIG_EFI, so maybe we should fall back to pulling this out of
screen_info and looking for a simple-framebuffer node in the CONFIG_OF
case?

(also maybe worth noting that on ARM/ARM64 we don't have
CONFIG_VGA_CONSOLE.. so there are a lot of fun permutations..)

BR,
-R
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Daniel Vetter July 11, 2017, 8:37 p.m. UTC | #7
On Tue, Jul 11, 2017 at 9:53 PM, Rob Clark <robdclark@gmail.com> wrote:
> On Tue, Jul 11, 2017 at 10:42 AM, Daniel Vetter <daniel@ffwll.ch> wrote:
>> On Tue, Jul 11, 2017 at 4:31 PM, Rob Clark <robdclark@gmail.com> wrote:
>>> On Tue, Jul 11, 2017 at 10:03 AM, Daniel Vetter <daniel@ffwll.ch> wrote:
>>>> On Tue, Jul 11, 2017 at 3:38 PM, Rob Clark <robdclark@gmail.com> wrote:
>>>>> +static unsigned long hijack_firmware_fb(struct drm_device *dev)
>>>>> +{
>>>>> +       struct msm_drm_private *priv = dev->dev_private;
>>>>> +       unsigned long size;
>>>>> +       int i;
>>>>> +
>>>>> +       /* if we have simplefb/efifb, find it's aperture and hijack
>>>>> +        * that before we kick out the firmware fb's.
>>>>> +        *
>>>>> +        * TODO we probably should hold registration_lock
>>>>> +        */
>>>>> +       for (i = 0; i < FB_MAX; i++) {
>>>>> +               struct fb_info *fb = get_fb_info(i);
>>>>> +
>>>>> +               if (IS_ERR_OR_NULL(fb))
>>>>> +                       continue;
>>>>> +
>>>>> +               if (!fb->apertures->count)
>>>>> +                       continue;
>>>>> +
>>>>> +               /* if we find efifb or simplefb, we are about to
>>>>> +                * kick them out, so hijack their memory:
>>>>> +                */
>>>>> +               if ((strcmp(fb->fix.id, "EFI VGA") == 0) ||
>>>>> +                               (strcmp(fb->fix.id, "simple") == 0)) {
>>>>> +
>>>>> +                       priv->vram.paddr = fb->apertures->ranges[0].base;
>>>>> +                       size = fb->apertures->ranges[0].size;
>>>>> +               }
>>>>> +
>>>>> +               put_fb_info(fb);
>>>>> +
>>>>> +               if (size)
>>>>> +                       return size;
>>>>> +       }
>>>>> +
>>>>> +       return 0;
>>>>> +}
>>>>
>>>> I think this should be a helper function in at least drm_fb_helper.c,
>>>> which would then fill in both base&size in a passed-in struct. But
>>>> yeah this seems a lot better than the old one.
>>>
>>> Yeah, I guess we could do that.. but probably not in drm_fb_helper.c
>>> since that is compile-time optional.  Better suggestions about where
>>> it should live?  If you have fbdev but not DRM_FBDEV_EMULATION you
>>> still want to do this, I think.  Otherwise we can't completely take
>>> over the display setup by firmware (ie. no way to create
>>> plane->state->fb).
>>
>> Hm right, maybe add a drm_fwfb_helper.c or so. If you look at
>> i915_kick_out_vgacon(), that might be another candidate for that file.
>> Putting it into fbdev itself seems like a bad idea, because
>> maintenance pains.
>
> Hmm, would it be weird to have an:
>
>   obj-$(CONFIG_FB) += drm_fbfw_helper.o
>
> in drm/Makefile?  Or is there a better way to do that?
>
> I'm also wondering a bit about the CONFIG_FB=n case.. you might still
> have CONFIG_EFI, so maybe we should fall back to pulling this out of
> screen_info and looking for a simple-framebuffer node in the CONFIG_OF
> case?
>
> (also maybe worth noting that on ARM/ARM64 we don't have
> CONFIG_VGA_CONSOLE.. so there are a lot of fun permutations..)

I'd include the source always (because of the above, e.g. kicking
vgacon doesn't depend on CONFIG_FB), and then we'll probably have to
sprinkle a pile of ugly #ifdef all over that file. Still better to
have these hacks in one place only at least.
-Daniel
diff mbox

Patch

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index f487437fb9d0..7c1ff26a3c13 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -304,6 +304,45 @@  static void kick_out_firmware_fb(void)
 	kfree(ap);
 }
 
+static unsigned long hijack_firmware_fb(struct drm_device *dev)
+{
+	struct msm_drm_private *priv = dev->dev_private;
+	unsigned long size;
+	int i;
+
+	/* if we have simplefb/efifb, find it's aperture and hijack
+	 * that before we kick out the firmware fb's.
+	 *
+	 * TODO we probably should hold registration_lock
+	 */
+	for (i = 0; i < FB_MAX; i++) {
+		struct fb_info *fb = get_fb_info(i);
+
+		if (IS_ERR_OR_NULL(fb))
+			continue;
+
+		if (!fb->apertures->count)
+			continue;
+
+		/* if we find efifb or simplefb, we are about to
+		 * kick them out, so hijack their memory:
+		 */
+		if ((strcmp(fb->fix.id, "EFI VGA") == 0) ||
+				(strcmp(fb->fix.id, "simple") == 0)) {
+
+			priv->vram.paddr = fb->apertures->ranges[0].base;
+			size = fb->apertures->ranges[0].size;
+		}
+
+		put_fb_info(fb);
+
+		if (size)
+			return size;
+	}
+
+	return 0;
+}
+
 static int msm_init_vram(struct drm_device *dev)
 {
 	struct msm_drm_private *priv = dev->dev_private;
@@ -335,39 +374,46 @@  static int msm_init_vram(struct drm_device *dev)
 		of_node_put(node);
 		if (ret)
 			return ret;
-		size = r.end - r.start;
+		size = r.end - r.start - 1;
 		DRM_INFO("using VRAM carveout: %lx@%pa\n", size, &r.start);
 
+	} else if ((size = hijack_firmware_fb(dev))) {
+		DRM_INFO("hijacking VRAM carveout: %lx@%pa\n",
+				size, &priv->vram.paddr);
+	} else if (!iommu_present(&platform_bus_type)) {
 		/* if we have no IOMMU, then we need to use carveout allocator.
 		 * Grab the entire CMA chunk carved out in early startup in
 		 * mach-msm:
 		 */
-	} else if (!iommu_present(&platform_bus_type)) {
 		DRM_INFO("using %s VRAM carveout\n", vram);
 		size = memparse(vram, NULL);
 	}
 
 	if (size) {
-		unsigned long attrs = 0;
-		void *p;
-
 		priv->vram.size = size;
 
-		drm_mm_init(&priv->vram.mm, 0, (size >> PAGE_SHIFT) - 1);
+		drm_mm_init(&priv->vram.mm, 0, (size >> PAGE_SHIFT));
 		spin_lock_init(&priv->vram.lock);
 
-		attrs |= DMA_ATTR_NO_KERNEL_MAPPING;
-		attrs |= DMA_ATTR_WRITE_COMBINE;
-
-		/* note that for no-kernel-mapping, the vaddr returned
-		 * is bogus, but non-null if allocation succeeded:
-		 */
-		p = dma_alloc_attrs(dev->dev, size,
-				&priv->vram.paddr, GFP_KERNEL, attrs);
-		if (!p) {
-			dev_err(dev->dev, "failed to allocate VRAM\n");
-			priv->vram.paddr = 0;
-			return -ENOMEM;
+		if (!priv->vram.paddr) {
+			unsigned long attrs = 0;
+			void *p;
+
+			attrs |= DMA_ATTR_NO_KERNEL_MAPPING;
+			attrs |= DMA_ATTR_WRITE_COMBINE;
+
+			/* note that for no-kernel-mapping, the vaddr returned
+			 * is bogus, but non-null if allocation succeeded:
+			 */
+			p = dma_alloc_attrs(dev->dev, size,
+					&priv->vram.paddr, GFP_KERNEL, attrs);
+			if (!p) {
+				dev_err(dev->dev, "failed to allocate VRAM\n");
+				priv->vram.paddr = 0;
+				return -ENOMEM;
+			}
+		} else {
+			request_region(priv->vram.paddr, size, "stolen");
 		}
 
 		dev_info(dev->dev, "VRAM: %08x->%08x\n",