From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrey Moiseev Subject: [PATCH] Input: i8042 - i8042_flush fix for a full 8042 buffer Date: Wed, 18 Sep 2013 16:35:56 +0400 Message-ID: <52399E2C.7000805@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-lb0-f180.google.com ([209.85.217.180]:51934 "EHLO mail-lb0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752027Ab3IRMgB (ORCPT ); Wed, 18 Sep 2013 08:36:01 -0400 Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: dmitry.torokhov@gmail.com Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Andrey Moiseev When 8042 internal data buffer is full, the driver erroneously decides that the controller is not present. I've already sent this 2 weeks ago, but that message received no comments. i8042_flush returns the number of flushed bytes, which is in 0 - I8042_BUFFER_SIZE range inclusive. Therefore, i8042_flush has no way to indicate an error. Moreover i8042_controller_check takes initially full buffer (i8042_flush returned I8042_BUFFER_SIZE) as a sign of absence of the controller. The fix: i8042_flush should perform one more status check after I8042_BUFFER_SIZE bytes have been read, and, if it succeeds, indicate the error by returning -1. i8042_controller_check should be changed appropriately. Signed-off-by: Andrey Moiseev --- diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c index 78e4de4..cdda786 100644 --- a/drivers/input/serio/i8042.c +++ b/drivers/input/serio/i8042.c @@ -222,29 +222,32 @@ static int i8042_wait_write(void) static int i8042_flush(void) { unsigned long flags; unsigned char data, str; int i = 0; spin_lock_irqsave(&i8042_lock, flags); - while (((str = i8042_read_status()) & I8042_STR_OBF) && (i < I8042_BUFFER_SIZE)) { + while (((str = i8042_read_status()) & I8042_STR_OBF) && (i <= I8042_BUFFER_SIZE)) { udelay(50); data = i8042_read_data(); i++; dbg("%02x <- i8042 (flush, %s)\n", data, str & I8042_STR_AUXDATA ? "aux" : "kbd"); } spin_unlock_irqrestore(&i8042_lock, flags); + if (i == I8042_BUFFER_SIZE + 1) + return -1; + return i; } /* * i8042_command() executes a command on the i8042. It also sends the input * parameter(s) of the commands to it, and receives the output value(s). The * parameters are to be stored in the param array, and the output is placed * into the same array. The number of the parameters and output values is * encoded in bits 8-11 of the command number. */ @@ -849,11 +852,11 @@ static int __init i8042_check_aux(void) static int i8042_controller_check(void) { - if (i8042_flush() == I8042_BUFFER_SIZE) { + if (i8042_flush() == -1) { pr_err("No controller found\n"); return -ENODEV; } return 0; } -- 1.8.4