From mboxrd@z Thu Jan  1 00:00:00 1970
From: LW@KARO-electronics.de (=?utf-8?Q?Lothar_Wa=C3=9Fmann?=)
Date: Wed, 18 Jul 2012 11:05:23 +0200
Subject: [PATCH] can: flexcan: add 2nd clock to support imx53 and newer
In-Reply-To: <500675C2.9090303@pengutronix.de>
References: <1342562748-24701-1-git-send-email-mkl@pengutronix.de>
 <50061B86.7080200@gmail.com> <500675C2.9090303@pengutronix.de>
Message-ID: <20486.31827.477680.302450@ipc1.ka-ro>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi,

Marc Kleine-Budde writes:
> On 07/18/2012 04:12 AM, Hui Wang wrote:
> > Marc Kleine-Budde wrote:
> >> From: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> >>
> >> This patch add support for a second clock to the flexcan driver. On
> >> modern
> >> freescale ARM cores like the imx53 and imx6q two clocks ("ipg" and "per")
> >> must be enabled in order to access the CAN core.
> >> -        clock_freq = clk_get_rate(clk);
> >>      }
> >>  
> >>      mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >> @@ -1039,7 +1052,8 @@ static int __devinit flexcan_probe(struct
> >> platform_device *pdev)
> >>          CAN_CTRLMODE_BERR_REPORTING;
> >>      priv->base = base;
> >>      priv->dev = dev;
> >> -    priv->clk = clk;
> >> +    priv->clk_ipg = clk_ipg;
> >> +    priv->clk_per = clk_per;
> >>      priv->pdata = pdev->dev.platform_data;
> >>      priv->devtype_data = devtype_data;
> >>  
> >> @@ -1067,9 +1081,11 @@ static int __devinit flexcan_probe(struct
> >> platform_device *pdev)
> >>   failed_map:
> >>      release_mem_region(mem->start, mem_size);
> >>   failed_get:
> >> -    if (clk)
> >> -        clk_put(clk);
> >>   failed_clock:
> >> +    if (clk_per)
> >>   
> > Use if (!IS_ERR(clk_per))
> 
> Yes, good catch.
> 
> Is it allowed to call clk_put with a NULL pointer? Both clocks can be
> NULL, if the frequency is defined via the device tree, this is case for
> powerpc.
> 
This has been discussed here already several times. Everything
returned by clk_get() that does not satisfy the IS_ERR() check, is a
valid clk cookie and can be used for the clk API calls.


Lothar Wa?mann
-- 
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