All of lore.kernel.org
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Manuel Lauss <manuel.lauss@gmail.com>,
	linux-mips@vger.kernel.org, linux-fbdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH] au1200fb: don't use DMA_ATTR_NON_CONSISTENT
Date: Tue, 25 Jun 2019 14:13:21 +0200	[thread overview]
Message-ID: <20190625121321.10197-1-hch@lst.de> (raw)

au1200fb allocates DMA memory using DMA_ATTR_NON_CONSISTENT, but never
calls dma_cache_sync to synchronize the memory between the CPU and the
device.  If it was use on a not cache coherent bus that would be fatal,
but as far as I can tell from the naming and the mips platform
implementation it always is used in cache coherent systems.  Remove
the DMA_ATTR_NON_CONSISTENT flag, which is a no-op in that case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/video/fbdev/au1200fb.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/video/fbdev/au1200fb.c b/drivers/video/fbdev/au1200fb.c
index 26caffb02b7e..265d3b45efd0 100644
--- a/drivers/video/fbdev/au1200fb.c
+++ b/drivers/video/fbdev/au1200fb.c
@@ -1234,7 +1234,7 @@ static int au1200fb_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
 	struct au1200fb_device *fbdev = info->par;
 
 	return dma_mmap_attrs(fbdev->dev, vma, fbdev->fb_mem, fbdev->fb_phys,
-			fbdev->fb_len, DMA_ATTR_NON_CONSISTENT);
+			fbdev->fb_len, 0);
 }
 
 static void set_global(u_int cmd, struct au1200_lcd_global_regs_t *pdata)
@@ -1692,8 +1692,7 @@ static int au1200fb_drv_probe(struct platform_device *dev)
 
 		fbdev->fb_mem = dmam_alloc_attrs(&dev->dev,
 				PAGE_ALIGN(fbdev->fb_len),
-				&fbdev->fb_phys, GFP_KERNEL,
-				DMA_ATTR_NON_CONSISTENT);
+				&fbdev->fb_phys, GFP_KERNEL, 0);
 		if (!fbdev->fb_mem) {
 			print_err("fail to allocate framebuffer (size: %dK))",
 				  fbdev->fb_len / 1024);
-- 
2.20.1


WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Manuel Lauss <manuel.lauss@gmail.com>,
	linux-mips@vger.kernel.org, linux-fbdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH] au1200fb: don't use DMA_ATTR_NON_CONSISTENT
Date: Tue, 25 Jun 2019 12:13:21 +0000	[thread overview]
Message-ID: <20190625121321.10197-1-hch@lst.de> (raw)

au1200fb allocates DMA memory using DMA_ATTR_NON_CONSISTENT, but never
calls dma_cache_sync to synchronize the memory between the CPU and the
device.  If it was use on a not cache coherent bus that would be fatal,
but as far as I can tell from the naming and the mips platform
implementation it always is used in cache coherent systems.  Remove
the DMA_ATTR_NON_CONSISTENT flag, which is a no-op in that case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/video/fbdev/au1200fb.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/video/fbdev/au1200fb.c b/drivers/video/fbdev/au1200fb.c
index 26caffb02b7e..265d3b45efd0 100644
--- a/drivers/video/fbdev/au1200fb.c
+++ b/drivers/video/fbdev/au1200fb.c
@@ -1234,7 +1234,7 @@ static int au1200fb_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
 	struct au1200fb_device *fbdev = info->par;
 
 	return dma_mmap_attrs(fbdev->dev, vma, fbdev->fb_mem, fbdev->fb_phys,
-			fbdev->fb_len, DMA_ATTR_NON_CONSISTENT);
+			fbdev->fb_len, 0);
 }
 
 static void set_global(u_int cmd, struct au1200_lcd_global_regs_t *pdata)
@@ -1692,8 +1692,7 @@ static int au1200fb_drv_probe(struct platform_device *dev)
 
 		fbdev->fb_mem = dmam_alloc_attrs(&dev->dev,
 				PAGE_ALIGN(fbdev->fb_len),
-				&fbdev->fb_phys, GFP_KERNEL,
-				DMA_ATTR_NON_CONSISTENT);
+				&fbdev->fb_phys, GFP_KERNEL, 0);
 		if (!fbdev->fb_mem) {
 			print_err("fail to allocate framebuffer (size: %dK))",
 				  fbdev->fb_len / 1024);
-- 
2.20.1

             reply	other threads:[~2019-06-25 12:13 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-25 12:13 Christoph Hellwig [this message]
2019-06-25 12:13 ` [PATCH] au1200fb: don't use DMA_ATTR_NON_CONSISTENT Christoph Hellwig
2019-06-26  7:16 ` Manuel Lauss
2019-06-26  7:16   ` Manuel Lauss
2019-07-23 15:35   ` Bartlomiej Zolnierkiewicz
2019-07-23 15:35     ` Bartlomiej Zolnierkiewicz

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190625121321.10197-1-hch@lst.de \
    --to=hch@lst.de \
    --cc=b.zolnierkie@samsung.com \
    --cc=linux-fbdev@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mips@vger.kernel.org \
    --cc=manuel.lauss@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.