Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964905AbbDIJ3i (ORCPT ); Thu, 9 Apr 2015 05:29:38 -0400 Received: from mail.kernel.org ([198.145.29.136]:42815 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755381AbbDIIzj (ORCPT ); Thu, 9 Apr 2015 04:55:39 -0400 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Axel Lin , Mark Brown , Zefan Li Subject: [PATCH 3.4 115/176] spi: dw: Fix detecting FIFO depth Date: Thu, 9 Apr 2015 16:46:03 +0800 Message-Id: <1428569224-23820-115-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1428569028-23762-1-git-send-email-lizf@kernel.org> References: <1428569028-23762-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2004 Lines: 56 From: Axel Lin 3.4.107-rc1 review patch. If anyone has any objections, please let me know. ------------------ commit d297933cc7fcfbaaf2d37570baac73287bf0357d upstream. Current code tries to find the highest valid fifo depth by checking the value it wrote to DW_SPI_TXFLTR. There are a few problems in current code: 1) There is an off-by-one in dws->fifo_len setting because it assumes the latest register write fails so the latest valid value should be fifo - 1. 2) We know the depth could be from 2 to 256 from HW spec, so it is not necessary to test fifo == 257. In the case fifo is 257, it means the latest valid setting is fifo = 256. So after the for loop iteration, we should check fifo == 2 case instead of fifo == 257 if detecting the FIFO depth fails. This patch fixes above issues. Signed-off-by: Axel Lin Reviewed-and-tested-by: Andy Shevchenko Signed-off-by: Mark Brown [lizf: Backported to 3.4: adjust context] Signed-off-by: Zefan Li --- 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 ff06b42..71ef1e4 100644 --- a/drivers/spi/spi-dw.c +++ b/drivers/spi/spi-dw.c @@ -780,13 +780,13 @@ static void spi_hw_init(struct dw_spi *dws) */ if (!dws->fifo_len) { u32 fifo; - for (fifo = 2; fifo <= 257; fifo++) { + for (fifo = 2; fifo <= 256; fifo++) { dw_writew(dws, DW_SPI_TXFLTR, fifo); if (fifo != dw_readw(dws, DW_SPI_TXFLTR)) break; } - dws->fifo_len = (fifo == 257) ? 0 : fifo; + dws->fifo_len = (fifo == 2) ? 0 : fifo - 1; dw_writew(dws, DW_SPI_TXFLTR, 0); } } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/