Messages in this thread | | | From | Arnd Bergmann <> | Date | Wed, 17 Nov 2021 08:37:58 +0100 | Subject | Re: [RFC 2/2] drm/msm/gem: Make use of the system cache |
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On Wed, Nov 17, 2021 at 12:16 AM Georgi Djakov <quic_c_gdjako@quicinc.com> wrote: > > Instead of writing to WC cmdstream buffers that go all the way to the main > memory, let's use the system cache to improve the performance. > > Signed-off-by: Georgi Djakov <quic_c_gdjako@quicinc.com> > --- > drivers/gpu/drm/msm/msm_gem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c > index 104fdfc14027..921a1c24721e 100644 > --- a/drivers/gpu/drm/msm/msm_gem.c > +++ b/drivers/gpu/drm/msm/msm_gem.c > @@ -214,7 +214,7 @@ void msm_gem_put_pages(struct drm_gem_object *obj) > static pgprot_t msm_gem_pgprot(struct msm_gem_object *msm_obj, pgprot_t prot) > { > if (msm_obj->flags & (MSM_BO_WC|MSM_BO_UNCACHED)) > - return pgprot_writecombine(prot); > + return pgprot_syscached(prot); > return prot; > }
Based on the definition in patch 1, doesn't this mean that 32-bit kernels degrade from writecombined to uncached, making them a lot slower?
My feeling about this series is that there should be a clearer definition of what exactly happens on systems with and without system cache.
Arnd
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