From patchwork Wed Mar 25 14:01:17 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 454453 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id D0A271400EA; Thu, 26 Mar 2015 01:05:35 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Yalw2-00034p-U6; Wed, 25 Mar 2015 14:05:30 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Yaluo-0002Tb-VZ for kernel-team@lists.ubuntu.com; Wed, 25 Mar 2015 14:04:14 +0000 Received: from [10.172.192.212] (helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1Yaluo-00049e-QB; Wed, 25 Mar 2015 14:04:14 +0000 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.16.y-ckt 104/165] spi: dw: revisit FIFO size detection again Date: Wed, 25 Mar 2015 14:01:17 +0000 Message-Id: <1427292138-7021-105-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1427292138-7021-1-git-send-email-luis.henriques@canonical.com> References: <1427292138-7021-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Cc: Mark Brown , Andy Shevchenko X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.16.7-ckt9 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Shevchenko commit 9d239d353c319f9ff884c287ce47feb7cdf60ddc upstream. The commit d297933cc7fc (spi: dw: Fix detecting FIFO depth) tries to fix the logic of the FIFO detection based on the description on the comments. However, there is a slight difference between numbers in TX Level and TX FIFO size. So, by specification the FIFO size would be in a range 2-256 bytes. From TX Level prospective it means we can set threshold in the range 0-(FIFO size - 1) bytes. Hence there are currently two issues: a) FIFO size 2 bytes is actually skipped since TX Level is 1 bit and could be either 0 or 1 byte; b) FIFO size is incorrectly decreased by 1 which already done by meaning of TX Level register. This patch fixes it eventually right. Fixes: d297933cc7fc (spi: dw: Fix detecting FIFO depth) Reviewed-by: Axel Lin Signed-off-by: Andy Shevchenko Signed-off-by: Mark Brown [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques --- drivers/spi/spi-dw.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c index 32a3718cc5b4..4fc4c20893e1 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -622,13 +622,13 @@ static void spi_hw_init(struct dw_spi *dws) */ if (!dws->fifo_len) { u32 fifo; - for (fifo = 2; fifo <= 256; fifo++) { + for (fifo = 1; fifo < 256; fifo++) { dw_writew(dws, DW_SPI_TXFLTR, fifo); if (fifo != dw_readw(dws, DW_SPI_TXFLTR)) break; } - dws->fifo_len = (fifo == 2) ? 0 : fifo - 1; + dws->fifo_len = (fifo == 1) ? 0 : fifo; dw_writew(dws, DW_SPI_TXFLTR, 0); } }