linux-kernel - [PATCH v2 1/2] dmaengine: edma: Implement protection for invalid max

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Date:   Tue, 3 Oct 2017 11:35:37 +0300
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     <vinod.koul@...el.com>, <dan.j.williams@...el.com>
CC:     <dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-omap@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: [PATCH v2 1/2] dmaengine: edma: Implement protection for invalid max_burst

Set the device's max_burst to 32767 (CIDX is 16bit signed value) so clients
can take this into consideration when setting up the transfer.

During slave transfer preparation check if the requested maxburst is valid.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
---
 drivers/dma/edma.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index a7ea20e7b8e9..9364a3ed345a 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -891,6 +891,10 @@ static int edma_slave_config(struct dma_chan *chan,
 	    cfg->dst_addr_width == DMA_SLAVE_BUSWIDTH_8_BYTES)
 		return -EINVAL;
 
+	if (cfg->src_maxburst > chan->device->max_burst ||
+	    cfg->dst_maxburst > chan->device->max_burst)
+		return -EINVAL;
+
 	memcpy(&echan->cfg, cfg, sizeof(echan->cfg));
 
 	return 0;
@@ -1868,6 +1872,7 @@ static void edma_dma_init(struct edma_cc *ecc, bool legacy_mode)
 	s_ddev->dst_addr_widths = EDMA_DMA_BUSWIDTHS;
 	s_ddev->directions |= (BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV));
 	s_ddev->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+	s_ddev->max_burst = SZ_32K - 1; /* CIDX: 16bit signed */
 
 	s_ddev->dev = ecc->dev;
 	INIT_LIST_HEAD(&s_ddev->channels);
-- 
2.14.2


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