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[67.185.54.80]) by smtp.gmail.com with ESMTPSA id z12sm43983750pfn.29.2019.07.29.12.53.04 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 29 Jul 2019 12:53:05 -0700 (PDT) From: Andrey Smirnov To: linux-serial@vger.kernel.org Cc: Andrey Smirnov , Stefan Agner , Bhuvanchandra DV , Chris Healy , Cory Tusar , Lucas Stach , Greg Kroah-Hartman , Jiri Slaby , linux-imx@nxp.com, linux-kernel@vger.kernel.org Subject: [PATCH 15/24] tty: serial: fsl_lpuart: Use cpu_relax() instead of barrier() Date: Mon, 29 Jul 2019 12:52:17 -0700 Message-Id: <20190729195226.8862-16-andrew.smirnov@gmail.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190729195226.8862-1-andrew.smirnov@gmail.com> References: <20190729195226.8862-1-andrew.smirnov@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use cpu_relax() instead of barrier() in a tight polling loops to make them a bit more idiomatic. Should also improve things on ARM64 a bit since cpu_relax() will expand into "yield" instruction there. Signed-off-by: Andrey Smirnov Cc: Stefan Agner Cc: Bhuvanchandra DV Cc: Chris Healy Cc: Cory Tusar Cc: Lucas Stach Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: linux-imx@nxp.com Cc: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- drivers/tty/serial/fsl_lpuart.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index dde5caf724ff..7a0f96952291 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -552,14 +552,14 @@ static void lpuart_wait_bit_set(struct uart_port *port, unsigned int offset, u8 bit) { while (!(readb(port->membase + offset) & bit)) - barrier(); + cpu_relax(); } static void lpuart32_wait_bit_set(struct uart_port *port, unsigned int offset, u32 bit) { while (!(lpuart32_read(port, offset) & bit)) - barrier(); + cpu_relax(); } #if defined(CONFIG_CONSOLE_POLL) -- 2.21.0