From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Kleine-Budde Subject: [PATCH 4/8] can: mcp251x: read-modify-write eflag only when needed Date: Mon, 18 Oct 2010 15:31:10 +0200 Message-ID: <1287408674-15412-5-git-send-email-mkl@pengutronix.de> References: <1287408674-15412-1-git-send-email-mkl@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Marc Kleine-Budde To: socketcan-core-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org Return-path: In-Reply-To: <1287408674-15412-1-git-send-email-mkl-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: socketcan-core-bounces-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org Errors-To: socketcan-core-bounces-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org List-Id: netdev.vger.kernel.org From: Sascha Hauer Use read-modify-write instead of a simple write to change the register contents, to close existing the race window between the original manual read and write. Signed-off-by: Sascha Hauer Signed-off-by: Marc Kleine-Budde Acked-by: Wolfgang Grandegger --- drivers/net/can/mcp251x.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/drivers/net/can/mcp251x.c b/drivers/net/can/mcp251x.c index 9b3466a..7e2f951 100644 --- a/drivers/net/can/mcp251x.c +++ b/drivers/net/can/mcp251x.c @@ -785,7 +785,8 @@ static irqreturn_t mcp251x_can_ist(int irq, void *dev_id) mcp251x_write_bits(spi, CANINTF, intf, 0x00); - mcp251x_write_reg(spi, EFLG, 0x00); + if (eflag) + mcp251x_write_bits(spi, EFLG, eflag, 0x00); /* Update can state */ if (eflag & EFLG_TXBO) { -- 1.7.0.4