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From: Huacai Chen <chenhuacai@loongson.cn>
To: Arnd Bergmann <arnd@arndb.de>, Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	David Airlie <airlied@linux.ie>, Jonathan Corbet <corbet@lwn.net>,
	Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-arch@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org, Xuefeng Li <lixuefeng@loongson.cn>,
	Yanteng Si <siyanteng@loongson.cn>,
	Huacai Chen <chenhuacai@gmail.com>,
	Jiaxun Yang <jiaxun.yang@flygoat.com>,
	Huacai Chen <chenhuacai@loongson.cn>
Subject: [PATCH V4 04/22] LoongArch: Add writecombine support for drm
Date: Mon, 27 Sep 2021 14:42:41 +0800	[thread overview]
Message-ID: <20210927064300.624279-5-chenhuacai@loongson.cn> (raw)
In-Reply-To: <20210927064300.624279-1-chenhuacai@loongson.cn>

LoongArch maintains cache coherency in hardware, but its WUC attribute
(Weak-ordered UnCached, which is similar to WC) is out of the scope of
cache coherency machanism. This means WUC can only used for write-only
memory regions.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
 drivers/gpu/drm/drm_vm.c         | 2 +-
 drivers/gpu/drm/ttm/ttm_module.c | 2 +-
 include/drm/drm_cache.h          | 8 ++++++++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
index e957d4851dc0..f024dc93939e 100644
--- a/drivers/gpu/drm/drm_vm.c
+++ b/drivers/gpu/drm/drm_vm.c
@@ -69,7 +69,7 @@ static pgprot_t drm_io_prot(struct drm_local_map *map,
 	pgprot_t tmp = vm_get_page_prot(vma->vm_flags);
 
 #if defined(__i386__) || defined(__x86_64__) || defined(__powerpc__) || \
-    defined(__mips__)
+    defined(__mips__) || defined(__loongarch__)
 	if (map->type == _DRM_REGISTERS && !(map->flags & _DRM_WRITE_COMBINING))
 		tmp = pgprot_noncached(tmp);
 	else
diff --git a/drivers/gpu/drm/ttm/ttm_module.c b/drivers/gpu/drm/ttm/ttm_module.c
index 7fcdef278c74..3dc43390e76b 100644
--- a/drivers/gpu/drm/ttm/ttm_module.c
+++ b/drivers/gpu/drm/ttm/ttm_module.c
@@ -60,7 +60,7 @@ pgprot_t ttm_prot_from_caching(enum ttm_caching caching, pgprot_t tmp)
 		tmp = pgprot_noncached(tmp);
 #endif
 #if defined(__ia64__) || defined(__arm__) || defined(__aarch64__) || \
-	defined(__powerpc__) || defined(__mips__)
+	defined(__powerpc__) || defined(__mips__) || defined(__loongarch__)
 	if (caching == ttm_write_combined)
 		tmp = pgprot_writecombine(tmp);
 	else
diff --git a/include/drm/drm_cache.h b/include/drm/drm_cache.h
index cc9de1632dd3..5c1059435369 100644
--- a/include/drm/drm_cache.h
+++ b/include/drm/drm_cache.h
@@ -67,6 +67,14 @@ static inline bool drm_arch_can_wc_memory(void)
 	 * optimization entirely for ARM and arm64.
 	 */
 	return false;
+#elif defined(CONFIG_LOONGARCH)
+	/*
+	 * LoongArch maintains cache coherency in hardware, but its WUC attribute
+	 * (Weak-ordered UnCached, which is similar to WC) is out of the scope of
+	 * cache coherency machanism. This means WUC can only used for write-only
+	 * memory regions.
+	 */
+	return false;
 #else
 	return true;
 #endif
-- 
2.27.0


  parent reply	other threads:[~2021-09-27  6:46 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-27  6:42 [PATCH V4 00/22] arch: Add basic LoongArch support Huacai Chen
2021-09-27  6:42 ` [PATCH V4 01/22] Documentation: LoongArch: Add basic documentations Huacai Chen
2021-09-27  6:42 ` [PATCH V4 02/22] Documentation/zh_CN: Add basic LoongArch documentations Huacai Chen
2021-09-27  6:42 ` [PATCH V4 03/22] LoongArch: Add elf-related definitions Huacai Chen
2021-09-27  6:42 ` Huacai Chen [this message]
2021-09-27  6:42 ` [PATCH V4 05/22] LoongArch: Add build infrastructure Huacai Chen
2021-09-27  6:42 ` [PATCH V4 06/22] LoongArch: Add CPU definition headers Huacai Chen
2021-09-30 15:30   ` Xi Ruoyao
2021-10-02 10:49     ` Huacai Chen
2021-09-27  6:42 ` [PATCH V4 07/22] LoongArch: Add atomic/locking headers Huacai Chen
2021-10-01 10:52   ` Peter Zijlstra
2021-10-02 11:47     ` Huacai Chen
2021-10-01 11:04   ` Peter Zijlstra
2021-10-02 11:05     ` Huacai Chen
2021-09-27  6:42 ` [PATCH V4 08/22] LoongArch: Add other common headers Huacai Chen
2021-09-27  6:42 ` [PATCH V4 09/22] LoongArch: Add boot and setup routines Huacai Chen
2021-09-27  6:52   ` Ard Biesheuvel
2021-09-29  3:24     ` Huacai Chen
2021-09-27  6:42 ` [PATCH V4 10/22] LoongArch: Add exception/interrupt handling Huacai Chen
2021-09-27  6:42 ` [PATCH V4 11/22] LoongArch: Add process management Huacai Chen
2021-10-03  2:48   ` Al Viro
2021-10-03  9:10     ` Huacai Chen
2021-09-27  6:42 ` [PATCH V4 12/22] LoongArch: Add memory management Huacai Chen
2021-09-27  6:42 ` [PATCH V4 13/22] LoongArch: Add system call support Huacai Chen
2021-09-27  6:42 ` [PATCH V4 14/22] LoongArch: Add signal handling support Huacai Chen
2021-10-03  2:29   ` Al Viro
2021-10-03  9:09     ` Huacai Chen
2021-09-27  6:42 ` [PATCH V4 15/22] LoongArch: Add elf and module support Huacai Chen
2021-09-27  6:42 ` [PATCH V4 16/22] LoongArch: Add misc common routines Huacai Chen
2021-10-01 11:03   ` Peter Zijlstra
2021-10-02 10:56     ` Huacai Chen
2021-09-27  6:42 ` [PATCH V4 17/22] LoongArch: Add some library functions Huacai Chen
2021-09-27  6:42 ` [PATCH V4 18/22] LoongArch: Add PCI controller support Huacai Chen
2021-09-27  6:42 ` [PATCH V4 19/22] LoongArch: Add VDSO and VSYSCALL support Huacai Chen
2021-09-30 15:43   ` Xi Ruoyao
2021-10-02 10:53     ` Huacai Chen
2021-10-02 12:13       ` Xi Ruoyao
2021-10-02 12:44         ` Huacai Chen
2021-09-27  6:42 ` [PATCH V4 20/22] LoongArch: Add multi-processor (SMP) support Huacai Chen
2021-09-27  6:42 ` [PATCH V4 21/22] LoongArch: Add Non-Uniform Memory Access (NUMA) support Huacai Chen
2021-09-27  6:42 ` [PATCH V4 22/22] LoongArch: Add Loongson-3 default config file Huacai Chen

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