Commit 9b7530cc authored by Linus Torvalds's avatar Linus Torvalds
Browse files

i915: cleanup coding horrors in i915_gem_gtt_pwrite() 



Yes, this will probably be switched over to a cleaner model anyway, but
in the meantime I don't want to see the 'unused variable' warnings that
come from the disgusting #ifdef code.  Make the special case be a nice
inlien function of its own, clean up the code, and make the warning go
away.

I wish people didn't write code that gets (valid) warnings from the
compiler, but I'll limit my fixes to code that I actually care about (in
this case just because I see the warning and it annoys me).

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1ae87786

drivers/gpu/drm/i915/i915_gem.c

+36 −23
Original line number Diff line number Diff line
@@ -171,6 +171,36 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data, 
	return 0;

}



/*

 * Try to write quickly with an atomic kmap. Return true on success.

 *

 * If this fails (which includes a partial write), we'll redo the whole

 * thing with the slow version.

 *

 * This is a workaround for the low performance of iounmap (approximate

 * 10% cpu cost on normal 3D workloads).  kmap_atomic on HIGHMEM kernels

 * happens to let us map card memory without taking IPIs.  When the vmap

 * rework lands we should be able to dump this hack.

 */

static inline int fast_user_write(unsigned long pfn, char __user *user_data, int l)

{

#ifdef CONFIG_HIGHMEM

	unsigned long unwritten;

	char *vaddr_atomic;



	vaddr_atomic = kmap_atomic_pfn(pfn, KM_USER0);

#if WATCH_PWRITE

	DRM_INFO("pwrite i %d o %d l %d pfn %ld vaddr %p\n",

		 i, o, l, pfn, vaddr_atomic);

#endif

	unwritten = __copy_from_user_inatomic_nocache(vaddr_atomic + o, user_data, l);

	kunmap_atomic(vaddr_atomic, KM_USER0);

	return !unwritten;

#else

	return 0;

#endif

}



static int

i915_gem_gtt_pwrite(struct drm_device *dev, struct drm_gem_object *obj,

		    struct drm_i915_gem_pwrite *args,
@@ -180,12 +210,7 @@ i915_gem_gtt_pwrite(struct drm_device *dev, struct drm_gem_object *obj, 
	ssize_t remain;

	loff_t offset;

	char __user *user_data;

	char __iomem *vaddr;

	char *vaddr_atomic;

	int i, o, l;

	int ret = 0;

	unsigned long pfn;

	unsigned long unwritten;



	user_data = (char __user *) (uintptr_t) args->data_ptr;

	remain = args->size;
@@ -209,6 +234,9 @@ i915_gem_gtt_pwrite(struct drm_device *dev, struct drm_gem_object *obj, 
	obj_priv->dirty = 1;



	while (remain > 0) {

		unsigned long pfn;

		int i, o, l;



		/* Operation in this page

		 *

		 * i = page number
@@ -223,25 +251,10 @@ i915_gem_gtt_pwrite(struct drm_device *dev, struct drm_gem_object *obj, 


		pfn = (dev->agp->base >> PAGE_SHIFT) + i;



#ifdef CONFIG_HIGHMEM

		/* This is a workaround for the low performance of iounmap

		 * (approximate 10% cpu cost on normal 3D workloads).

		 * kmap_atomic on HIGHMEM kernels happens to let us map card

		 * memory without taking IPIs.  When the vmap rework lands

		 * we should be able to dump this hack.

		 */

		vaddr_atomic = kmap_atomic_pfn(pfn, KM_USER0);

#if WATCH_PWRITE

		DRM_INFO("pwrite i %d o %d l %d pfn %ld vaddr %p\n",

			 i, o, l, pfn, vaddr_atomic);

#endif

		unwritten = __copy_from_user_inatomic_nocache(vaddr_atomic + o,

							      user_data, l);

		kunmap_atomic(vaddr_atomic, KM_USER0);

		if (!fast_user_write(pfn, user_data, l)) {

			unsigned long unwritten;

			char __iomem *vaddr;



		if (unwritten)

#endif /* CONFIG_HIGHMEM */

		{

			vaddr = ioremap_wc(pfn << PAGE_SHIFT, PAGE_SIZE);

#if WATCH_PWRITE

			DRM_INFO("pwrite slow i %d o %d l %d "

CRA Git | Maintained and supported by SUSTech CRA and CCSE