Re: [RFC PATCH 5/7] ARM: davinci: i2c: add OF support

Hello Grant,

Grant Likely wrote:

On Tue, Jan 24, 2012 at 10:51:50AM +0100, Sylwester Nawrocki wrote:

quoted

Hello Heiko,

On 01/24/2012 08:18 AM, Heiko Schocher wrote:

quoted

quoted

On 01/23/2012 09:56 AM, Heiko Schocher wrote:

quoted

add of support for the davinci i2c driver.

Signed-off-by: Heiko Schocher<redacted>
Cc: davinci-linux-open-source-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org
Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: Ben Dooks<redacted>
Cc: Wolfram Sang<redacted>
Cc: Grant Likely<grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
Cc: Sekhar Nori<redacted>
Cc: Wolfgang Denk<redacted>
---
  .../devicetree/bindings/arm/davinci/i2c.txt        |   39 ++++++++++++++++++
  drivers/i2c/busses/i2c-davinci.c                   |   43 ++++++++++++++++++++
  2 files changed, 82 insertions(+), 0 deletions(-)
  create mode 100644 Documentation/devicetree/bindings/arm/davinci/i2c.txt

[...]

quoted

Moreover you seem to overwrite platform device name and id,

		if (!of_property_read_u32(pdev->dev.of_node, "id",
+			&prop)) {
+			pdev->id = prop;
+			pdev->dev.init_name = kzalloc(20, GFP_KERNEL);
+			sprintf((char *)pdev->dev.init_name,
+				"i2c_davinci.%d", pdev->id);

I'm not sure if it is a good practice.

No, it is not good practice.  At this point the device is already
registered.  Changing the value of pdev->id will cause problems in the
core code because the /sysfs files will have already been created.

quoted

If you want to pre-define platform
device name (likely for the clock API to work), it might be more appropriate
to use OF_DEV_AUXDATA in the machine code, until there are clock bindings
available.

Yes, use OF_DEV_AUXDATA, but *only* if you need it for hooking up
clocks, regulators, or similar.  Don't use it just because you want
the device to have a different name for cosmetic reasons.  The need
for AUXDATA should go away once the DT clock binding code is merged.

I now use OF_DEV_AUXDATA in board code, "id" nor "cell-index" used:

struct of_dev_auxdata enbw_cmc_auxdata_lookup[] __initdata = {
        OF_DEV_AUXDATA("ti,davinci-i2c", 0x01c22000, "i2c_davinci.1", NULL),
        OF_DEV_AUXDATA("ti,davinci-i2c", 0x01e28000, "i2c_davinci.2", NULL),
        {}
};

This is needed for hooking up clocks, see:
arch/arm/mach-davinci/da850.c
static struct clk_lookup da850_clks
[...]
        CLK("i2c_davinci.1",    NULL,           &i2c0_clk),
[...]
        CLK("i2c_davinci.2",    NULL,           &i2c1_clk),

bye,
Heiko
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