[PATCH v4 07/15] dmaengine: dw-edma: Improve number of channels check

Gustavo Pimentel
2021-02-03T21:59:43Z

It was added some extra checks to ensure that the driver doesn't try to
use more DMA channels than actually are available in hardware.

Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
---
drivers/dma/dw-edma/dw-edma-core.c | 21 +++++++++------------
drivers/dma/dw-edma/dw-edma-core.h | 2 ++
2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index 0fe3835..5495cf7 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c
@@ -914,19 +914,16 @@ int dw_edma_probe(struct dw_edma_chip *chip)

raw_spin_lock_init(&dw->lock);

- if (!dw->wr_ch_cnt) {
- /* Find out how many write channels are supported by hardware */
- dw->wr_ch_cnt = dw_edma_v0_core_ch_count(dw, EDMA_DIR_WRITE);
- if (!dw->wr_ch_cnt)
- return -EINVAL;
- }
+ dw->wr_ch_cnt = min_t(u16, dw->wr_ch_cnt,
+ dw_edma_v0_core_ch_count(dw, EDMA_DIR_WRITE));
+ dw->wr_ch_cnt = min_t(u16, dw->wr_ch_cnt, EDMA_MAX_WR_CH);

- if (!dw->rd_ch_cnt) {
- /* Find out how many read channels are supported by hardware */
- dw->rd_ch_cnt = dw_edma_v0_core_ch_count(dw, EDMA_DIR_READ);
- if (!dw->rd_ch_cnt)
- return -EINVAL;
- }
+ dw->rd_ch_cnt = min_t(u16, dw->rd_ch_cnt,
+ dw_edma_v0_core_ch_count(dw, EDMA_DIR_READ));
+ dw->rd_ch_cnt = min_t(u16, dw->rd_ch_cnt, EDMA_MAX_RD_CH);
+
+ if (!dw->wr_ch_cnt && !dw->rd_ch_cnt)
+ return -EINVAL;

dev_vdbg(dev, "Channels:\twrite=%d, read=%d\n",
dw->wr_ch_cnt, dw->rd_ch_cnt);
diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-edma-core.h
index f72ebaa..650b1c7 100644
--- a/drivers/dma/dw-edma/dw-edma-core.h
+++ b/drivers/dma/dw-edma/dw-edma-core.h
@@ -15,6 +15,8 @@
#include "../virt-dma.h"

#define EDMA_LL_SZ 24
+#define EDMA_MAX_WR_CH 8
+#define EDMA_MAX_RD_CH 8

enum dw_edma_dir {
EDMA_DIR_WRITE = 0,
--
2.7.4