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From: "Lothar Waßmann" <LW@KARO-electronics.de>
To: Andrew Lunn <andrew@lunn.ch>
Cc: viresh kumar <viresh.linux@gmail.com>,
	Russell King - ARM Linux <linux@arm.linux.org.uk>,
	sshtylyov@mvista.com, spear-devel@list.st.com,
	linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org,
	mturquette@linaro.org, akpm@linux-foundation.org,
	jgarzik@redhat.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH V3 07/12] ata/sata_mv: Remove conditional compilation of clk code
Date: Wed, 25 Apr 2012 08:43:45 +0200	[thread overview]
Message-ID: <20375.40225.227084.644318@ipc1.ka-ro> (raw)
In-Reply-To: <20120425052802.GF13489@lunn.ch>

Hi,

Andrew Lunn writes:
> > This is what i was thinking too and thats why floated this version of patch.
> > But as Andrew said, clk API support is enabled for them, but still they
> > don't have a clk for sata. To get this working, there are two solutions:
> > - Create dummy clk for sata for that platform, so clk_get doesn't fail.
> > - Check for error before every call to clk APIs after clk_get().
> > 
> > Andrew favored the second one. Which means, even on platforms
> > with clk API defined and clk enable required, if there are some issues
> > with lookup table, and clk_get() fails, system may hang when registers
> > are accessed. For this i favored first one.
> 
> I'm not too sure how you are going to achieve 1)
> 
> config SATA_MV
>         tristate "Marvell SATA support"
>         help
>           This option enables support for the Marvell Serial ATA family.
>           Currently supports 88SX[56]0[48][01] PCI(-X) chips,
>           as well as the newer [67]042 PCI-X/PCIe and SOC devices.
> 
> So this driver can be used with anything which has a PCI(-X) or PCIe
> bus, or Orion SoC and a few PowerPC SoCs.
> 
> The SoCs are not too bad, we know which ones they are and we can add
> dummy entries to their device tree. However, how do you want to handle
> the PCI devices? Create the dummy entry somewhere in the middle of the
> PCI core?
> 
> Thought not.
> 
AFAICT the PCI archs do not have HAVE_CLK enabled. Thus they will have
a dummy clk API in place that provides the driver with a non-error
clk_get() return value.


Lothar Waßmann
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  reply	other threads:[~2012-04-25  6:44 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <cover.1335266056.git.viresh.kumar@st.com>
2012-04-24 11:21 ` [PATCH V3 06/12] ata/pata_arasan: Remove conditional compilation of clk code Viresh Kumar
2012-04-24 11:21 ` [PATCH V3 07/12] ata/sata_mv: " Viresh Kumar
2012-04-24 12:00   ` Andrew Lunn
2012-04-24 12:51     ` Lothar Waßmann
2012-04-24 13:42     ` viresh kumar
2012-04-24 14:29       ` Andrew Lunn
2012-04-24 17:02         ` viresh kumar
2012-04-25  5:42           ` Andrew Lunn
2012-04-24 17:05         ` viresh kumar
2012-04-24 20:18       ` Russell King - ARM Linux
2012-04-25  3:02         ` viresh kumar
2012-04-25  5:28           ` Andrew Lunn
2012-04-25  6:43             ` Lothar Waßmann [this message]
2012-04-25  7:14               ` Andrew Lunn
2012-04-25  8:35                 ` Lothar Waßmann
2012-04-25  9:31                   ` Andrew Lunn
2012-04-25 10:37                     ` Russell King - ARM Linux
2012-04-25 11:24         ` Andrew Lunn

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