4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Rafał Miłecki <rafal@xxxxxxxxxx>
commit 940ec770c295682993d1cccce3081fd7c74fece8 upstream.
Fixing/optimizing bcm_qspi_bspi_read() performance introduced two
changes:
1) It added a loop to read all requested data using multiple BSPI ops.
2) It bumped max size of a single BSPI block request from 256 to 512 B.
The later change resulted in occasional BSPI timeouts causing a
regression.
For some unknown reason hardware doesn't always handle reads as expected
when using 512 B chunks. In such cases it may happen that BSPI returns
amount of requested bytes without the last 1-3 ones. It provides the
remaining bytes later but doesn't raise an interrupt until another LR
start.
Switching back to 256 B reads fixes that problem and regression.
Fixes: 345309fa7c0c ("spi: bcm-qspi: Fix bcm_qspi_bspi_read() performance")
Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/spi/spi-bcm-qspi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/spi/spi-bcm-qspi.c
+++ b/drivers/spi/spi-bcm-qspi.c
@@ -88,7 +88,7 @@
#define BSPI_BPP_MODE_SELECT_MASK BIT(8)
#define BSPI_BPP_ADDR_SELECT_MASK BIT(16)
-#define BSPI_READ_LENGTH 512
+#define BSPI_READ_LENGTH 256
/* MSPI register offsets */
#define MSPI_SPCR0_LSB 0x000
