spi: respect the maximum segment size of DMA device

andy-shev · broonie · commit df88e91bbfd1 · 2016-03-09T16:33:52.000+07:00
The device which is actually does DMA may have a limitation of the maximum
segment size. Respect this setting when preparing scatter-gather list.

Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
@@ -702,6 +702,7 @@ static int spi_map_buf(struct spi_master *master, struct device *dev,
 		       enum dma_data_direction dir)
 {
 	const bool vmalloced_buf = is_vmalloc_addr(buf);
+	unsigned int max_seg_size = dma_get_max_seg_size(dev);
 	int desc_len;
 	int sgs;
 	struct page *vm_page;
@@ -710,10 +711,10 @@ static int spi_map_buf(struct spi_master *master, struct device *dev,
 	int i, ret;
 
 	if (vmalloced_buf) {
-		desc_len = PAGE_SIZE;
+		desc_len = min_t(int, max_seg_size, PAGE_SIZE);
 		sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
 	} else {
-		desc_len = master->max_dma_len;
+		desc_len = min_t(int, max_seg_size, master->max_dma_len);
 		sgs = DIV_ROUND_UP(len, desc_len);
 	}
 
@@ -739,7 +740,6 @@ static int spi_map_buf(struct spi_master *master, struct device *dev,
 			sg_set_buf(&sgt->sgl[i], sg_buf, min);
 		}
 
-
 		buf += min;
 		len -= min;
 	}

Original file line number	Diff line number	Diff line change
`@@ -702,6 +702,7 @@ static int spi_map_buf(struct spi_master master, struct device dev,`
`702`	`702`	`enum dma_data_direction dir)`
`703`	`703`	`{`
`704`	`704`	`const bool vmalloced_buf = is_vmalloc_addr(buf);`
	`705`	`+ unsigned int max_seg_size = dma_get_max_seg_size(dev);`
`705`	`706`	`int desc_len;`
`706`	`707`	`int sgs;`
`707`	`708`	`struct page *vm_page;`
`@@ -710,10 +711,10 @@ static int spi_map_buf(struct spi_master master, struct device dev,`
`710`	`711`	`int i, ret;`
`711`	`712`
`712`	`713`	`if (vmalloced_buf) {`
`713`		`- desc_len = PAGE_SIZE;`
	`714`	`+ desc_len = min_t(int, max_seg_size, PAGE_SIZE);`
`714`	`715`	`sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);`
`715`	`716`	`} else {`
`716`		`- desc_len = master->max_dma_len;`
	`717`	`+ desc_len = min_t(int, max_seg_size, master->max_dma_len);`
`717`	`718`	`sgs = DIV_ROUND_UP(len, desc_len);`
`718`	`719`	`}`
`719`	`720`
`@@ -739,7 +740,6 @@ static int spi_map_buf(struct spi_master master, struct device dev,`
`739`	`740`	`sg_set_buf(&sgt->sgl[i], sg_buf, min);`
`740`	`741`	`}`
`741`	`742`
`742`		`-`
`743`	`743`	`buf += min;`
`744`	`744`	`len -= min;`
`745`	`745`	`}`