Hey Tvrtko,
Are you saying when adding drm_clflush_virt_range(addr, sizeof(addr),
this function forces an x86 code path only? If that is the case,
drm_clflush_virt_range(addr, sizeof(addr) currently has ifdefs that
seperate out x86 and powerpc, so we can add an ifdef for arm in the near
future when needed.
On 2022-01-31 6:55 a.m., Tvrtko Ursulin wrote:
On 28/01/2022 22:10, Michael Cheng wrote:
Use drm_clflush_virt_range instead of clflushopt and remove the memory
barrier, since drm_clflush_virt_range takes care of that.
Signed-off-by: Michael Cheng <michael.cheng@xxxxxxxxx>
---
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 498b458fd784..0854276ff7ba 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -1332,10 +1332,8 @@ static void *reloc_vaddr(struct i915_vma *vma,
static void clflush_write32(u32 *addr, u32 value, unsigned int
flushes)
{
if (unlikely(flushes & (CLFLUSH_BEFORE | CLFLUSH_AFTER))) {
- if (flushes & CLFLUSH_BEFORE) {
- clflushopt(addr);
- mb();
- }
+ if (flushes & CLFLUSH_BEFORE)
+ drm_clflush_virt_range(addr, sizeof(addr));
*addr = value;
@@ -1347,7 +1345,7 @@ static void clflush_write32(u32 *addr, u32
value, unsigned int flushes)
* to ensure ordering of clflush wrt to the system.
*/
if (flushes & CLFLUSH_AFTER)
- clflushopt(addr);
+ drm_clflush_virt_range(addr, sizeof(addr));
} else
*addr = value;
}
Slightly annoying thing here (maybe in some other patches from the
series as well) is that the change adds a function call to x86 only
code path, because relocations are not supported on discrete as per:
static in
eb_validate_vma(...)
/* Relocations are disallowed for all platforms after TGL-LP.
This
* also covers all platforms with local memory.
*/
if (entry->relocation_count &&
GRAPHICS_VER(eb->i915) >= 12 && !IS_TIGERLAKE(eb->i915))
return -EINVAL;
How acceptable would be, for the whole series, to introduce a static
inline i915 cluflush wrapper and so be able to avoid functions calls
on x86? Is this something that has been discussed and discounted already?
Regards,
Tvrtko
P.S. Hmm I am now reminded of my really old per platform build
patches. With them you would be able to compile out large portions of
the driver when building for ARM. Probably like a 3rd if my memory
serves me right.
