linux-kernel - [PATCH 2/9] spi_mpc83xx: Quieten down the "Requested speed is too low" message

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Message-ID: <20090430234823.GB7901@oksana.dev.rtsoft.ru>
Date:	Fri, 1 May 2009 03:48:23 +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 2/9] spi_mpc83xx: Quieten down the "Requested speed is too
	low" message

When a platform is running at high frequencies it's not always
possible to scale-down a frequency to a requested value, and using
mmc_spi driver this leads to the following printk flood during card
polling:

  ...
  mmc_spi spi32766.0: Requested speed is too low: 400000 Hz. Will use
  520828 Hz instead.
  mmc_spi spi32766.0: Requested speed is too low: 400000 Hz. Will use
  520828 Hz instead.
  ...

Fix this by using WARN_ONCE(), it's better than the flood, and also
better than turning dev_err() into dev_dbg(), since we actually want
to warn that some things may not work correctly.

Signed-off-by: Anton Vorontsov <avorontsov@...mvista.com>
---
 drivers/spi/spi_mpc83xx.c |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/spi/spi_mpc83xx.c b/drivers/spi/spi_mpc83xx.c
index f4573a9..08b49d2 100644
--- a/drivers/spi/spi_mpc83xx.c
+++ b/drivers/spi/spi_mpc83xx.c
@@ -14,6 +14,7 @@
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
+#include <linux/bug.h>
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/completion.h>
@@ -275,12 +276,12 @@ int mpc83xx_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
 	if ((mpc83xx_spi->spibrg / hz) > 64) {
 		cs->hw_mode |= SPMODE_DIV16;
 		pm = mpc83xx_spi->spibrg / (hz * 64);
-		if (pm > 16) {
-			dev_err(&spi->dev, "Requested speed is too "
-				"low: %d Hz. Will use %d Hz instead.\n",
-				hz, mpc83xx_spi->spibrg / 1024);
+
+		WARN_ONCE(pm > 16, "%s: Requested speed is too low: %d Hz. "
+			  "Will use %d Hz instead.\n", dev_name(&spi->dev),
+			  hz, mpc83xx_spi->spibrg / 1024);
+		if (pm > 16)
 			pm = 16;
-		}
 	} else
 		pm = mpc83xx_spi->spibrg / (hz * 4);
 	if (pm)
-- 
1.6.2.2

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