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* [PATCH] dma-contiguous: CMA: give precedence to cmdline
@ 2020-01-10 17:19 ` Nicolas Saenz Julienne
  0 siblings, 0 replies; 8+ messages in thread
From: Nicolas Saenz Julienne @ 2020-01-10 17:19 UTC (permalink / raw)
  To: Christoph Hellwig, Marek Szyprowski, Robin Murphy
  Cc: iommu, phil, linux-kernel, Nicolas Saenz Julienne

Although the device tree might contain a reserved-memory DT node
dedicated as the default CMA pool, users might want to change CMA's
parameters using the kernel command line for debugging purposes and
whatnot. Honor this by bypassing the reserved memory CMA setup, which
will ultimately end up freeing the memblock and allow the command line
CMA configuration routine to run.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---

NOTE: Tested this on arm and arm64 with the Raspberry Pi 4.

 kernel/dma/contiguous.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index daa4e6eefdde..8bc6f2d670f9 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -302,9 +302,16 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
 	phys_addr_t align = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
 	phys_addr_t mask = align - 1;
 	unsigned long node = rmem->fdt_node;
+	bool default_cma = of_get_flat_dt_prop(node, "linux,cma-default", NULL);
 	struct cma *cma;
 	int err;
 
+	if (size_cmdline != -1 && default_cma) {
+		pr_info("Reserved memory: bypass %s node, using cmdline CMA params instead\n",
+			rmem->name);
+		return -EBUSY;
+	}
+
 	if (!of_get_flat_dt_prop(node, "reusable", NULL) ||
 	    of_get_flat_dt_prop(node, "no-map", NULL))
 		return -EINVAL;
@@ -322,7 +329,7 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
 	/* Architecture specific contiguous memory fixup. */
 	dma_contiguous_early_fixup(rmem->base, rmem->size);
 
-	if (of_get_flat_dt_prop(node, "linux,cma-default", NULL))
+	if (default_cma)
 		dma_contiguous_set_default(cma);
 
 	rmem->ops = &rmem_cma_ops;
-- 
2.24.1

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^ permalink raw reply related	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2020-01-30 16:11 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-01-10 17:19 [PATCH] dma-contiguous: CMA: give precedence to cmdline Nicolas Saenz Julienne
2020-01-10 17:19 ` Nicolas Saenz Julienne
2020-01-10 17:36 ` Phil Elwell
2020-01-10 17:36   ` Phil Elwell
2020-01-30 13:42 ` Christoph Hellwig
2020-01-30 13:42   ` Christoph Hellwig
2020-01-30 16:11   ` Nicolas Saenz Julienne
2020-01-30 16:11     ` Nicolas Saenz Julienne

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