linux-kernel - Re: [PATCH] drm: add cache support for arm64

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Date:   Tue, 30 Jul 2019 16:59:10 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel <dri-devel@...ts.freedesktop.org>
Cc:     Rob Clark <robdclark@...omium.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm: add cache support for arm64

On Tue, Jul 30, 2019 at 4:01 PM Rob Clark <robdclark@...il.com> wrote:
>
> From: Rob Clark <robdclark@...omium.org>
>
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> ---
> Not sure about 32b arm, but at least for aarch64 this is relatively
> easy.  So lets at least enable for arm64.

hmm, bleh, I thought this was too easy.. I hadn't noticed that (even
though driver was =m) CONFIG_DRM was =y

Can we make drm_cache.o built-in even if the rest of drm is a module?

BR,
-R

>
>  drivers/gpu/drm/drm_cache.c | 20 +++++++++++++++++---
>  1 file changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c
> index 3bd76e918b5d..90105c637797 100644
> --- a/drivers/gpu/drm/drm_cache.c
> +++ b/drivers/gpu/drm/drm_cache.c
> @@ -69,6 +69,14 @@ static void drm_cache_flush_clflush(struct page *pages[],
>  }
>  #endif
>
> +#if defined(__powerpc__)
> +static void __flush_dcache_area(void *addr, size_t len)
> +{
> +       flush_dcache_range((unsigned long)addr,
> +                          (unsigned long)addr + PAGE_SIZE);
> +}
> +#endif
> +
>  /**
>   * drm_clflush_pages - Flush dcache lines of a set of pages.
>   * @pages: List of pages to be flushed.
> @@ -90,7 +98,7 @@ drm_clflush_pages(struct page *pages[], unsigned long num_pages)
>         if (wbinvd_on_all_cpus())
>                 pr_err("Timed out waiting for cache flush\n");
>
> -#elif defined(__powerpc__)
> +#elif defined(__powerpc__) || defined(CONFIG_ARM64)
>         unsigned long i;
>         for (i = 0; i < num_pages; i++) {
>                 struct page *page = pages[i];
> @@ -100,8 +108,7 @@ drm_clflush_pages(struct page *pages[], unsigned long num_pages)
>                         continue;
>
>                 page_virtual = kmap_atomic(page);
> -               flush_dcache_range((unsigned long)page_virtual,
> -                                  (unsigned long)page_virtual + PAGE_SIZE);
> +               __flush_dcache_area(page_virtual, PAGE_SIZE);
>                 kunmap_atomic(page_virtual);
>         }
>  #else
> @@ -135,6 +142,13 @@ drm_clflush_sg(struct sg_table *st)
>
>         if (wbinvd_on_all_cpus())
>                 pr_err("Timed out waiting for cache flush\n");
> +#elif defined(CONFIG_ARM64)
> +       struct sg_page_iter sg_iter;
> +
> +       for_each_sg_page(st->sgl, &sg_iter, st->nents, 0) {
> +               struct page *p = sg_page_iter_page(&sg_iter);
> +               drm_clflush_pages(&p, 1);
> +       }
>  #else
>         pr_err("Architecture has no drm_cache.c support\n");
>         WARN_ON_ONCE(1);
> --
> 2.21.0
>