linux-kernel - [PATCH 3.13.y-ckt 26/80] spi: dw: Fix detecting FIFO depth

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1426804568-2907-27-git-send-email-kamal@canonical.com>
Date:	Thu, 19 Mar 2015 15:35:14 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Axel Lin <axel.lin@...ics.com>, Mark Brown <broonie@...nel.org>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.13.y-ckt 26/80] spi: dw: Fix detecting FIFO depth

3.13.11-ckt17 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Axel Lin <axel.lin@...ics.com>

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 <axel.lin@...ics.com>
Reviewed-and-tested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 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 84b1238..265f084 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -762,13 +762,13 @@ 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@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/