From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= Date: Thu, 11 Oct 2018 09:07:31 +0200 Subject: [PATCH FIX] spi: bcm-qspi: switch back to reading flash using smaller chunks MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Cc: stable@vger.kernel.org # 4.11+ --- 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