On 21.03.2022 16:07, Lucas De Marchi wrote:
> Now Cc'ing Daniel properly
>
> Lucas De Marchi
>
> On Mon, Mar 21, 2022 at 04:00:56PM -0700, Lucas De Marchi wrote:
> > +Thomas Zimmermann and +Daniel Vetter
> >
> > Could you take a look below regarding the I/O to I/O memory access?
> >
> > On Thu, Mar 03, 2022 at 11:30:11PM +0530, Balasubramani Vivekanandan wrote:
> > > memcpy_from_wc functions in i915_memcpy.c will be removed and replaced
> > > by the implementation in drm_cache.c.
> > > Updated to use the functions provided by drm_cache.c.
> > >
> > > v2: check if the source and destination memory address is from local
> > > memory or system memory and initialize the iosys_map accordingly
> > > (Lucas)
> > >
> > > Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
> > > Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
> > > Cc: Thomas Hellstr_m <thomas.hellstrom@xxxxxxxxxxxxxxx>
> > >
> > > Signed-off-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@xxxxxxxxx>
> > > ---
> > > .../drm/i915/selftests/intel_memory_region.c | 41 +++++++++++++------
> > > 1 file changed, 28 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/selftests/intel_memory_region.c b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
> > > index ba32893e0873..d16ecb905f3b 100644
> > > --- a/drivers/gpu/drm/i915/selftests/intel_memory_region.c
> > > +++ b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
> > > @@ -7,6 +7,7 @@
> > > #include <linux/sort.h>
> > >
> > > #include <drm/drm_buddy.h>
> > > +#include <drm/drm_cache.h>
> > >
> > > #include "../i915_selftest.h"
> > >
> > > @@ -1133,7 +1134,7 @@ static const char *repr_type(u32 type)
> > >
> > > static struct drm_i915_gem_object *
> > > create_region_for_mapping(struct intel_memory_region *mr, u64 size, u32 type,
> > > - void **out_addr)
> > > + struct iosys_map *out_addr)
> > > {
> > > struct drm_i915_gem_object *obj;
> > > void *addr;
> > > @@ -1153,7 +1154,11 @@ create_region_for_mapping(struct intel_memory_region *mr, u64 size, u32 type,
> > > return addr;
> > > }
> > >
> > > - *out_addr = addr;
> > > + if (i915_gem_object_is_lmem(obj))
> > > + iosys_map_set_vaddr_iomem(out_addr, (void __iomem *)addr);
> > > + else
> > > + iosys_map_set_vaddr(out_addr, addr);
> > > +
> > > return obj;
> > > }
> > >
> > > @@ -1164,24 +1169,33 @@ static int wrap_ktime_compare(const void *A, const void *B)
> > > return ktime_compare(*a, *b);
> > > }
> > >
> > > -static void igt_memcpy_long(void *dst, const void *src, size_t size)
> > > +static void igt_memcpy_long(struct iosys_map *dst, struct iosys_map *src,
> > > + size_t size)
> > > {
> > > - unsigned long *tmp = dst;
> > > - const unsigned long *s = src;
> > > + unsigned long *tmp = dst->is_iomem ?
> > > + (unsigned long __force *)dst->vaddr_iomem :
> > > + dst->vaddr;
> >
> > if we access vaddr_iomem/vaddr we basically break the promise of
> > abstracting system and I/O memory. There is no point in receiving
> > struct iosys_map as argument and then break the abstraction.
> >
Hi Lucas,
I didn't attempt to convert the memory access using iosys_map
interfaces to abstract system and I/O memory, in this patch. The
intention of passing iosys_map structures instead of raw pointers in the
test functions is for the benefit of igt_memcpy_from_wc() test function.
igt_memcpy_from_wc() requires iosys_map variables for passing it to
drm_memcpy_from_wc().
In the other test functions, though it receives iosys_map structures I
have retained the behavior same as earlier by converting back the
iosys_map structures to pointers.
I made a short try to use iosys_map structures to perform the memory
copy inside other test functions, but I dropped it after I realized that
their is support lacking for (a) mentioned below in your comment.
Since it requires some discussion to bring in the support for (a), I did
not proceed with it.
Regards,
Bala
> > > + const unsigned long *s = src->is_iomem ?
> > > + (unsigned long __force *)src->vaddr_iomem :
> > > + src->vaddr;
> > >
> > > size = size / sizeof(unsigned long);
> > > while (size--)
> > > *tmp++ = *s++;
> >
> >
> > so we basically want to copy from one place to the other on a word
> > boundary. And it may be
> >
> > a) I/O -> I/O or
> > b) system -> I/O or
> > c) I/O -> system
> >
> > (b) and (c) should work, but AFAICS (a) is not possible with the current
> > iosys-map API. Not even the underlying APIs have that abstracted. Both
> > memcpy_fromio() and memcpy_toio() expect one of them to be RAM (system
> > memory)
> >
> > I remember seeing people using a temporary in buffer in system memory
> > for proxying the copy. But maybe we need an abstraction for that?
> > Also adding Thomas Zimmermann here for that question.
> >
> > and since this is a selftest testing the performance of the memcpy from
> > one memory region to the other, it would be good to have this test
> > executed to a) make sure it still works and b) record in the commit
> > message any possible slow down we are incurring.
> >
> > thanks
> > Lucas De Marchi
> >
> >
> > > }
> > >
> > > -static inline void igt_memcpy(void *dst, const void *src, size_t size)
> > > +static inline void igt_memcpy(struct iosys_map *dst, struct iosys_map *src,
> > > + size_t size)
> > > {
> > > - memcpy(dst, src, size);
> > > + memcpy(dst->is_iomem ? (void __force *)dst->vaddr_iomem : dst->vaddr,
> > > + src->is_iomem ? (void __force *)src->vaddr_iomem : src->vaddr,
> > > + size);
> > > }
> > >
> > > -static inline void igt_memcpy_from_wc(void *dst, const void *src, size_t size)
> > > +static inline void igt_memcpy_from_wc(struct iosys_map *dst, struct iosys_map *src,
> > > + size_t size)
> > > {
> > > - i915_memcpy_from_wc(dst, src, size);
> > > + drm_memcpy_from_wc(dst, src, size);
> > > }
> > >
> > > static int _perf_memcpy(struct intel_memory_region *src_mr,
> > > @@ -1191,7 +1205,8 @@ static int _perf_memcpy(struct intel_memory_region *src_mr,
> > > struct drm_i915_private *i915 = src_mr->i915;
> > > const struct {
> > > const char *name;
> > > - void (*copy)(void *dst, const void *src, size_t size);
> > > + void (*copy)(struct iosys_map *dst, struct iosys_map *src,
> > > + size_t size);
> > > bool skip;
> > > } tests[] = {
> > > {
> > > @@ -1205,11 +1220,11 @@ static int _perf_memcpy(struct intel_memory_region *src_mr,
> > > {
> > > "memcpy_from_wc",
> > > igt_memcpy_from_wc,
> > > - !i915_has_memcpy_from_wc(),
> > > + !drm_memcpy_fastcopy_supported(),
> > > },
> > > };
> > > struct drm_i915_gem_object *src, *dst;
> > > - void *src_addr, *dst_addr;
> > > + struct iosys_map src_addr, dst_addr;
> > > int ret = 0;
> > > int i;
> > >
> > > @@ -1237,7 +1252,7 @@ static int _perf_memcpy(struct intel_memory_region *src_mr,
> > >
> > > t0 = ktime_get();
> > >
> > > - tests[i].copy(dst_addr, src_addr, size);
> > > + tests[i].copy(&dst_addr, &src_addr, size);
> > >
> > > t1 = ktime_get();
> > > t[pass] = ktime_sub(t1, t0);
> > > --
> > > 2.25.1
> > >
