dma-contiguous: CMA: give precedence to cmdline
diff mbox series

Message ID 20200110171933.15014-1-nsaenzjulienne@suse.de
State Accepted
Commit 8c8c5a4994a306c217fd061cbfc5903399fd4c1c
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Series
  • dma-contiguous: CMA: give precedence to cmdline
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Commit Message

Nicolas Saenz Julienne Jan. 10, 2020, 5:19 p.m. UTC
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(-)

Comments

Phil Elwell Jan. 10, 2020, 5:36 p.m. UTC | #1
Hi Nicolas,

On 10/01/2020 17:19, Nicolas Saenz Julienne wrote:
> 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;
> 

For what it's worth,

Reviewed-by: Phil Elwell <phil@raspberrypi.org>

Phil
Christoph Hellwig Jan. 30, 2020, 1:42 p.m. UTC | #2
I've picked this up for Linux 5.6, sorry for the delay.
Nicolas Saenz Julienne Jan. 30, 2020, 4:11 p.m. UTC | #3
On Thu Jan 30, 2020 at 2:42 PM, Christoph Hellwig wrote:
> I've picked this up for Linux 5.6, sorry for the delay.

Thanks!

Patch
diff mbox series

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;