From: Christoph Hellwig <hch@lst.de>
Date: Fri, 6 Oct 2023 13:17:54 +0000 (+0200)
Subject: dma-direct: warn when coherent allocations aren't supported
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=63f067e33c996a6e4d9a34d138116a43105182f1;p=linux.git

dma-direct: warn when coherent allocations aren't supported

Log a warning once when dma_alloc_coherent fails because the platform
does not support coherent allocations at all.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
Tested-by: Greg Ungerer <gerg@linux-m68k.org>
---

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 9657ef7c055ea..ed3056eb20b8b 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -240,8 +240,10 @@ void *dma_direct_alloc(struct device *dev, size_t size,
 		 */
 		set_uncached = IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED);
 		remap = IS_ENABLED(CONFIG_DMA_DIRECT_REMAP);
-		if (!set_uncached && !remap)
+		if (!set_uncached && !remap) {
+			pr_warn_once("coherent DMA allocations not supported on this platform.\n");
 			return NULL;
+		}
 	}
 
 	/*