linux-kernel - [PATCH 4/8] dma-buf: heaps: Add ECC protection flags

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Message-Id: <20240515-dma-buf-ecc-heap-v1-4-54cbbd049511@kernel.org>
Date: Wed, 15 May 2024 15:56:59 +0200
From: Maxime Ripard <mripard@...nel.org>
To: Rob Herring <robh@...nel.org>, Saravana Kannan <saravanak@...gle.com>, 
 Sumit Semwal <sumit.semwal@...aro.org>, 
 Benjamin Gaignard <benjamin.gaignard@...labora.com>, 
 Brian Starkey <Brian.Starkey@....com>, John Stultz <jstultz@...gle.com>, 
 "T.J. Mercier" <tjmercier@...gle.com>, 
 Christian König <christian.koenig@....com>
Cc: Mattijs Korpershoek <mkorpershoek@...libre.com>, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
 linaro-mm-sig@...ts.linaro.org, Maxime Ripard <mripard@...nel.org>
Subject: [PATCH 4/8] dma-buf: heaps: Add ECC protection flags

Some systems run with ECC enabled on the memory by default, but with
some memory regions with ECC disabled to mitigate the downsides of
enabling ECC (reduced performances, increased memory usage) for buffers
that don't require it.

Let's create some allocation flags to ask for a particular ECC setup
when allocate a dma-buf through a heap.

Signed-off-by: Maxime Ripard <mripard@...nel.org>
---
 drivers/dma-buf/dma-heap.c    | 4 ++++
 include/uapi/linux/dma-heap.h | 5 +++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
index 84ae708fafe7..a96c1865b627 100644
--- a/drivers/dma-buf/dma-heap.c
+++ b/drivers/dma-buf/dma-heap.c
@@ -106,10 +106,14 @@ static long dma_heap_ioctl_allocate(struct file *file, void *data)
 		return -EINVAL;

 	if (heap_allocation->heap_flags & ~DMA_HEAP_VALID_HEAP_FLAGS)
 		return -EINVAL;

+	if ((heap_allocation->heap_flags & DMA_HEAP_FLAG_ECC_PROTECTED) &&
+	    (heap_allocation->heap_flags & DMA_HEAP_FLAG_ECC_UNPROTECTED))
+		return -EINVAL;
+
 	fd = dma_heap_buffer_alloc(heap, heap_allocation->len,
 				   heap_allocation->fd_flags,
 				   heap_allocation->heap_flags);
 	if (fd < 0)
 		return fd;
diff --git a/include/uapi/linux/dma-heap.h b/include/uapi/linux/dma-heap.h
index 6f84fa08e074..677b6355552d 100644
--- a/include/uapi/linux/dma-heap.h
+++ b/include/uapi/linux/dma-heap.h
@@ -16,12 +16,13 @@
  */

 /* Valid FD_FLAGS are O_CLOEXEC, O_RDONLY, O_WRONLY, O_RDWR */
 #define DMA_HEAP_VALID_FD_FLAGS (O_CLOEXEC | O_ACCMODE)

-/* Currently no heap flags */
-#define DMA_HEAP_VALID_HEAP_FLAGS (0)
+#define DMA_HEAP_FLAG_ECC_PROTECTED	BIT(0)
+#define DMA_HEAP_FLAG_ECC_UNPROTECTED	BIT(1)
+#define DMA_HEAP_VALID_HEAP_FLAGS (DMA_HEAP_FLAG_ECC_PROTECTED | DMA_HEAP_FLAG_ECC_UNPROTECTED)

 /**
  * struct dma_heap_allocation_data - metadata passed from userspace for
  *                                      allocations
  * @len:		size of the allocation

-- 
2.44.0