linux-kernel - [PATCH 3/9] spi_mpc83xx: Add small delay after asserting chip-select line

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Message-ID: <20090430234824.GC7901@oksana.dev.rtsoft.ru>
Date:	Fri, 1 May 2009 03:48:24 +0400
From:	Anton Vorontsov <avorontsov@...mvista.com>
To:	Kumar Gala <galak@...nel.crashing.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	David Brownell <dbrownell@...rs.sourceforge.net>,
	linuxppc-dev@...abs.org, spi-devel-general@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: [PATCH 3/9] spi_mpc83xx: Add small delay after asserting
	chip-select line

This is needed for some underlaying GPIO controllers that may be
a bit slow, or if chip-select signal need some time to stabilize.

For what it's worth, we already have the similar delay for
chip-select de-assertion case.

Signed-off-by: Anton Vorontsov <avorontsov@...mvista.com>
---
 drivers/spi/spi_mpc83xx.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/spi/spi_mpc83xx.c b/drivers/spi/spi_mpc83xx.c
index 08b49d2..d378d5e 100644
--- a/drivers/spi/spi_mpc83xx.c
+++ b/drivers/spi/spi_mpc83xx.c
@@ -383,8 +383,10 @@ static void mpc83xx_spi_work(struct work_struct *work)
 					break;
 			}
 
-			if (cs_change)
+			if (cs_change) {
 				mpc83xx_spi_chipselect(spi, BITBANG_CS_ACTIVE);
+				ndelay(nsecs);
+			}
 			cs_change = t->cs_change;
 			if (t->len)
 				status = mpc83xx_spi_bufs(spi, t);
-- 
1.6.2.2

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