| From 940ec770c295682993d1cccce3081fd7c74fece8 Mon Sep 17 00:00:00 2001 |
| From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl> |
| Date: Thu, 11 Oct 2018 09:42:17 +0200 |
| Subject: spi: bcm-qspi: switch back to reading flash using smaller chunks |
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| |
| From: Rafał Miłecki <rafal@milecki.pl> |
| |
| 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@milecki.pl> |
| Signed-off-by: Mark Brown <broonie@kernel.org> |
| Cc: stable@vger.kernel.org |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| 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 |
| @@ -89,7 +89,7 @@ |
| #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 |
