linux-kernel - [PATCH v15 08/19] drm/etnaviv: Fix wrong caching mode being used for non writecombine buffers

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Message-ID: <20240908094357.291862-9-sui.jingfeng@linux.dev>
Date: Sun,  8 Sep 2024 17:43:46 +0800
From: Sui Jingfeng <sui.jingfeng@...ux.dev>
To: Lucas Stach <l.stach@...gutronix.de>
Cc: Christian Gmeiner <christian.gmeiner@...il.com>,
	Russell King <linux+etnaviv@...linux.org.uk>,
	dri-devel@...ts.freedesktop.org,
	etnaviv@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Sui Jingfeng <sui.jingfeng@...ux.dev>
Subject: [PATCH v15 08/19] drm/etnaviv: Fix wrong caching mode being used for non writecombine buffers

In the etnaviv_gem_vmap_impl() function, the driver vmap whatever buffers
with write combine(WC) page property. This is incorrect, as some platforms
are cached coherent. Cached buffers should be mapped with cached page
property.

Fixes: a0a5ab3e99b8 ("drm/etnaviv: call correct function when trying to vmap a DMABUF")
Signed-off-by: Sui Jingfeng <sui.jingfeng@...ux.dev>
---
 drivers/gpu/drm/etnaviv/etnaviv_gem.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index 1fd2cff20ef4..b899aea64e22 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -393,6 +393,7 @@ static void etnaviv_gem_object_vunmap(struct drm_gem_object *obj,
 static void *etnaviv_gem_vmap_impl(struct etnaviv_gem_object *obj)
 {
 	struct page **pages;
+	pgprot_t prot;
 
 	lockdep_assert_held(&obj->lock);
 
@@ -400,8 +401,19 @@ static void *etnaviv_gem_vmap_impl(struct etnaviv_gem_object *obj)
 	if (IS_ERR(pages))
 		return NULL;
 
-	return vmap(pages, obj->base.size >> PAGE_SHIFT,
-			VM_MAP, pgprot_writecombine(PAGE_KERNEL));
+	switch (obj->flags) {
+	case ETNA_BO_CACHED:
+		prot = PAGE_KERNEL;
+		break;
+	case ETNA_BO_UNCACHED:
+		prot = pgprot_noncached(PAGE_KERNEL);
+		break;
+	case ETNA_BO_WC:
+	default:
+		prot = pgprot_writecombine(PAGE_KERNEL);
+	}
+
+	return vmap(pages, obj->base.size >> PAGE_SHIFT, VM_MAP, prot);
 }
 
 static inline enum dma_data_direction etnaviv_op_to_dma_dir(u32 op)
-- 
2.43.0