linux-kernel - [PATCH] dma-buf: heaps: remove duplicated cache sync

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Date:   Mon, 30 Aug 2021 18:01:38 +0800
From:   <guangming.cao@...iatek.com>
To:     Sumit Semwal <sumit.semwal@...aro.org>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Liam Mark <lmark@...eaurora.org>,
        Laura Abbott <labbott@...hat.com>,
        Brian Starkey <Brian.Starkey@....com>,
        John Stultz <john.stultz@...aro.org>,
        Christian König <christian.koenig@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "open list:DMA-BUF HEAPS FRAMEWORK" <linux-media@...r.kernel.org>,
        "open list:DMA-BUF HEAPS FRAMEWORK" <dri-devel@...ts.freedesktop.org>,
        "moderated list:DMA-BUF HEAPS FRAMEWORK" 
        <linaro-mm-sig@...ts.linaro.org>,
        open list <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>
CC:     <wsd_upstream@...iatek.com>,
        Guangming Cao <Guangming.Cao@...iatek.com>
Subject: [PATCH] dma-buf: heaps: remove duplicated cache sync

From: Guangming Cao <Guangming.Cao@...iatek.com>

Current flow, one dmabuf maybe call cache sync many times if
it has beed mapped more than one time.

Is there any case that attachments of one dmabuf will points to
different memory? If not, seems do sync only one time is more better.

Signed-off-by: Guangming Cao <Guangming.Cao@...iatek.com>
---
 drivers/dma-buf/heaps/system_heap.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
index 23a7e74ef966..909ef652a8c8 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -162,9 +162,10 @@ static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
 		invalidate_kernel_vmap_range(buffer->vaddr, buffer->len);
 
 	list_for_each_entry(a, &buffer->attachments, list) {
-		if (!a->mapped)
-			continue;
-		dma_sync_sgtable_for_cpu(a->dev, a->table, direction);
+		if (a->mapped) {
+			dma_sync_sgtable_for_cpu(a->dev, a->table, direction);
+			break;
+		}
 	}
 	mutex_unlock(&buffer->lock);
 
@@ -183,9 +184,10 @@ static int system_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
 		flush_kernel_vmap_range(buffer->vaddr, buffer->len);
 
 	list_for_each_entry(a, &buffer->attachments, list) {
-		if (!a->mapped)
-			continue;
-		dma_sync_sgtable_for_device(a->dev, a->table, direction);
+		if (!a->mapped) {
+			dma_sync_sgtable_for_device(a->dev, a->table, direction);
+			break;
+		}
 	}
 	mutex_unlock(&buffer->lock);
 
-- 
2.17.1