The patch titled atmel_spi throughput improvement has been removed from the -mm tree. Its filename was atmel_spi-throughput-improvement.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: atmel_spi throughput improvement From: Haavard Skinnemoen <hskinnemoen@xxxxxxxxx> Don't insert (undesirable) delays between consecutive words (DLYBCT) or when activating chipselects (DLYBS). Removing the between-word delays improves the performance of bulk transfers (such as mtd_dataflash, m25p80, mmc_spi) significantly. In one test, the improvement was a factor of more than eight! (The large DLYBCT value came from the legacy at91 SPI driver, and it's not clear why it used such a huge value.) Signed-off-by: Haavard Skinnemoen <hskinnemoen@xxxxxxxxx> Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/spi/atmel_spi.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff -puN drivers/spi/atmel_spi.c~atmel_spi-throughput-improvement drivers/spi/atmel_spi.c --- a/drivers/spi/atmel_spi.c~atmel_spi-throughput-improvement +++ a/drivers/spi/atmel_spi.c @@ -490,9 +490,14 @@ static int atmel_spi_setup(struct spi_de if (!(spi->mode & SPI_CPHA)) csr |= SPI_BIT(NCPHA); - /* TODO: DLYBS and DLYBCT */ - csr |= SPI_BF(DLYBS, 10); - csr |= SPI_BF(DLYBCT, 10); + /* DLYBS is mostly irrelevant since we manage chipselect using GPIOs. + * + * DLYBCT would add delays between words, slowing down transfers. + * It could potentially be useful to cope with DMA bottlenecks, but + * in those cases it's probably best to just use a lower bitrate. + */ + csr |= SPI_BF(DLYBS, 0); + csr |= SPI_BF(DLYBCT, 0); /* chipselect must have been muxed as GPIO (e.g. in board setup) */ npcs_pin = (unsigned int)spi->controller_data; _ Patches currently in -mm which might be from hskinnemoen@xxxxxxxxx are origin.patch git-avr32.patch git-mtd.patch sanitize-the-type-of-struct-useru_ar0.patch add-cmpxchg_local-to-avr32.patch tty-let-architectures-override-the-user-kernel-macros.patch maintainers-add-haavard-as-maintainer-of-the-atmel_serial-driver.patch atmel_serial-clean-up-the-code.patch atmel_serial-use-cpu_relax-when-busy-waiting.patch atmel_serial-use-existing-console-options-only-if-brg-is-running.patch atmel_serial-fix-bugs-in-probe-error-path-and-remove.patch atmel_serial-split-the-interrupt-handler.patch atmel_serial-add-dma-support.patch atmel_serial-add-dma-support-fix.patch atmel_serial-fix-broken-rx-buffer-allocation.patch atmel_serial-use-container_of-instead-of-direct-cast.patch atmel_serial-show-tty-name-in-proc-interrupts.patch basic-pwm-driver-for-avr32-and-at91.patch basic-pwm-driver-for-avr32-and-at91-fix.patch pwm-led-driver.patch - To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html