The patch titled atmel_serial: use cpu_relax() when busy-waiting has been added to the -mm tree. Its filename is atmel_serial-use-cpu_relax-when-busy-waiting.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: atmel_serial: use cpu_relax() when busy-waiting From: Haavard Skinnemoen <hskinnemoen@xxxxxxxxx> Replace two instances of barrier() with cpu_relax() since that's the right thing to do when busy-waiting. This does not actually change anything since cpu_relax() is defined as barrier() on both ARM and AVR32. Signed-off-by: Haavard Skinnemoen <hskinnemoen@xxxxxxxxx> Acked-by: Andrew Victor <linux@xxxxxxxxxxxx> Tested-by: Marc Pignat <marc.pignat@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/serial/atmel_serial.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN drivers/serial/atmel_serial.c~atmel_serial-use-cpu_relax-when-busy-waiting drivers/serial/atmel_serial.c --- a/drivers/serial/atmel_serial.c~atmel_serial-use-cpu_relax-when-busy-waiting +++ a/drivers/serial/atmel_serial.c @@ -616,7 +616,7 @@ static void atmel_set_termios(struct uar imr = UART_GET_IMR(port); UART_PUT_IDR(port, -1); while (!(UART_GET_CSR(port) & ATMEL_US_TXEMPTY)) - barrier(); + cpu_relax(); /* disable receiver and transmitter */ UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS); @@ -795,7 +795,7 @@ void __init atmel_register_uart_fns(stru static void atmel_console_putchar(struct uart_port *port, int ch) { while (!(UART_GET_CSR(port) & ATMEL_US_TXRDY)) - barrier(); + cpu_relax(); UART_PUT_CHAR(port, ch); } _ Patches currently in -mm which might be from hskinnemoen@xxxxxxxxx are git-avr32.patch fix-timerfd-breakage-on-avr32-was-re-fix-variable-use-in-avr32-pte_alloc_one.patch git-mtd.patch gpiolib-add-drivers-gpio-directory.patch gpiolib-add-gpio-provider-infrastructure.patch gpiolib-update-documentation-gpiotxt.patch gpiolib-pxa-platform-support.patch gpiolib-pcf857x-i2c-gpio-expander-support.patch gpiolib-mcp23s08-spi-gpio-expander-support.patch gpiolib-pca9539-i2c-gpio-expander-support.patch gpiolib-deprecate-obsolete-pca9539-driver.patch gpiolib-avr32-at32ap-platform-support.patch config_highpte-vs-sub-page-page-tables-avr32-fix.patch read_current_time-cleanups.patch fix-__const_udelay-declaration-and-definition-mismatches.patch atmel_spi-throughput-improvement.patch atmel_spi-chain-dma-transfers.patch atmel_spi-chain-dma-transfers-update.patch atmel_spi-fix-dmachain-oops-with-debug-enabled.patch add-have_oprofile.patch atmel_lcdfb-validate-display-timings.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-use-container_of-instead-of-direct-cast.patch atmel_serial-show-tty-name-in-proc-interrupts.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