Hi Javier,
On 2017-02-17 22:13, Javier Martinez Canillas wrote:
On 02/14/2017 04:52 AM, Marek Szyprowski wrote:
It turned out that all versions of MFC v6+ hardware doesn't have a strict
requirement for ALL buffers to be allocated on higher addresses than the
firmware base like it was documented for MFC v5. This requirement is true
only for the device and per-context buffers. All video data buffers can be
allocated anywhere for all MFC v6+ versions. Basing on this fact, the
special DMA configuration based on two reserved memory regions is not
really needed for MFC v6+ devices, because the memory requirements for the
firmware, device and per-context buffers can be fulfilled by the simple
probe-time pre-allocated block allocator instroduced in previous patch.
s/instroduced/introduced
This patch enables support for such pre-allocated block based allocator
always for MFC v6+ devices. Due to the limitations of the memory management
subsystem the largest supported size of the pre-allocated buffer when no
CMA (Contiguous Memory Allocator) is enabled is 4MiB.
This patch also removes the requirement to provide two reserved memory
regions for MFC v6+ devices in device tree. Now the driver is fully
functional without them.
Great!
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
The patch looks good to me though and it works on my tests,
I've just one comment below.
Reviewed-by: Javier Martinez Canillas <javier@xxxxxxxxxxxxxxx>
Tested-by: Javier Martinez Canillas <javier@xxxxxxxxxxxxxxx>
Documentation/devicetree/bindings/media/s5p-mfc.txt | 2 +-
drivers/media/platform/s5p-mfc/s5p_mfc.c | 9 ++++++---
2 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/Documentation/devicetree/bindings/media/s5p-mfc.txt b/Documentation/devicetree/bindings/media/s5p-mfc.txt
index 2c901286d818..d3404b5d4d17 100644
--- a/Documentation/devicetree/bindings/media/s5p-mfc.txt
+++ b/Documentation/devicetree/bindings/media/s5p-mfc.txt
@@ -28,7 +28,7 @@ Optional properties:
- memory-region : from reserved memory binding: phandles to two reserved
memory regions, first is for "left" mfc memory bus interfaces,
second if for the "right" mfc memory bus, used when no SYSMMU
- support is available
+ support is available; used only by MFC v5 present in Exynos4 SoCs
Obsolete properties:
- samsung,mfc-r, samsung,mfc-l : support removed, please use memory-region
diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc.c b/drivers/media/platform/s5p-mfc/s5p_mfc.c
index 8fc6fe4ba087..36f0aec2a1b3 100644
--- a/drivers/media/platform/s5p-mfc/s5p_mfc.c
+++ b/drivers/media/platform/s5p-mfc/s5p_mfc.c
@@ -1178,9 +1178,12 @@ static void s5p_mfc_unconfigure_2port_memory(struct s5p_mfc_dev *mfc_dev)
static int s5p_mfc_configure_common_memory(struct s5p_mfc_dev *mfc_dev)
{
struct device *dev = &mfc_dev->plat_dev->dev;
- unsigned long mem_size = SZ_8M;
+ unsigned long mem_size = SZ_4M;
unsigned int bitmap_size;
+ if (IS_ENABLED(CONFIG_DMA_CMA) || exynos_is_iommu_available(dev))
+ mem_size = SZ_8M;
+
if (mfc_mem_size)
mem_size = memparse(mfc_mem_size, NULL);
The driver allows the user to set mem_size > SZ_4M using the s5p_mfc.mem
parameter even when CMA ins't enabled and IOMMU isn't available. Maybe it
should fail early instead and notify the user what's missing?
It will notify user that driver failed to preallocate memory. 4M is the
upper
limit for standard kernel configuration, but afair there were some kconfig
knobs to force kernel to use larger buckets for buddy allocator (what
changes
the limit). Frankly I would leave it as is.
If user wants to specify s5p-mfc.mem, he already has some knowledge how to
configure the kernel. I don't think that driver should check all possible
scenarios of failing and give detailed explanation what was configured
wrong. You can also enable CMA and configure the 8MiB of the default global
area. In such configuration preallocation of mfc firmware buffer will also
fail. Should the driver care about it? IMO it is enough to tell user that
preallocating of given megabytes failed.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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