linux-kernel - Re: [PATCH v10] i2c-designware: make SDA hold time configurable

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Message-Id: <201307031343.11647.arnd@arndb.de>
Date:	Wed, 3 Jul 2013 13:43:11 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Wolfram Sang <wsa@...-dreams.de>
Cc:	Christian Ruppert <christian.ruppert@...lis.com>,
	Rob Herring <robherring2@...il.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	linux-i2c@...r.kernel.org,
	"Ben Dooks (embedded platforms)" <ben-linux@...ff.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Landley <rob@...dley.net>,
	devicetree-discuss@...ts.ozlabs.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Vineet Gupta <Vineet.Gupta1@...opsys.com>,
	Pierrick Hascoet <pierrick.hascoet@...lis.com>
Subject: Re: [PATCH v10] i2c-designware: make SDA hold time configurable

On Wednesday 26 June 2013, Wolfram Sang wrote:
>   On Wed, Jun 26, 2013 at 10:55:06AM +0200, Christian Ruppert wrote:
> > This patch makes the SDA hold time configurable through device tree.
> > 
> > Signed-off-by: Christian Ruppert <christian.ruppert@...lis.com>
> > Signed-off-by: Pierrick Hascoet <pierrick.hascoet@...lis.com>
> 
> Applied to for-next, thanks for keeping at it and providing lots of
> useful information. Much appreciated!

Sorry, but I got a regression that I didn't find reported elsewhere
so far, even though it breaks a lot of the ARM defconfig builds:

drivers/built-in.o: In function `dw_i2c_probe':
/git/arm-soc/drivers/i2c/busses/i2c-designware-platdrv.c:125: undefined reference to `__udivdi3'

I suspect you want something like the change below.

Signed-off-by: Arnd Bergmann <arnd@...db.de>

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index def79b5..57e3a07 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -119,10 +119,13 @@ static int dw_i2c_probe(struct platform_device *pdev)
 	if (pdev->dev.of_node) {
 		u32 ht = 0;
 		u32 ic_clk = dev->get_clk_rate_khz(dev);
+		u64 hold_time;
 
 		of_property_read_u32(pdev->dev.of_node,
 					"i2c-sda-hold-time-ns", &ht);
-		dev->sda_hold_time = ((u64)ic_clk * ht + 500000) / 1000000;
+		hold_time = (u64)ic_clk * ht + 500000;
+		do_div(hold_time, 1000000);
+		dev->sda_hold_time = hold_time;
 	}
 
 	dev->functionality =
--
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