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- From 940ec770c295682993d1cccce3081fd7c74fece8 Mon Sep 17 00:00:00 2001
- From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <[email protected]>
- Date: Thu, 11 Oct 2018 09:42:17 +0200
- Subject: [PATCH] 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 <[email protected]>
- Signed-off-by: Mark Brown <[email protected]>
- Cc: [email protected]
- ---
- 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
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