Re: [PATCH] USB: ohci-at91: add usb_clk for transition to commonclk framework

From: boris brezillon
Date: Thu Aug 01 2013 - 11:15:01 EST

On 01/08/2013 16:39, Alan Stern wrote:
On Thu, 1 Aug 2013, Boris BREZILLON wrote:

The AT91 PMC (Power Management Controller) provides an USB clock used by
USB Full Speed host (ohci) and USB Full Speed device (udc).
The usb drivers (ohci and udc) must configure this clock to 48Mhz.
This configuration was formely done in mach-at91/clock.c, but this
implementation will be removed when moving to common clk framework.

This patch adds support for usb clock retrieval and configuration, and is
backward compatible with the current at91 clk implementation (if usb clk
is not found, it does not configure/enable it).

Signed-off-by: Boris BREZILLON <b.brezillon@xxxxxxxxxxx>
@@ -163,6 +169,8 @@ static int usb_hcd_at91_probe(const struct hc_driver *driver,
goto err5;
+ uclk = clk_get(&pdev->dev, "usb_clk");
What happens if uclk isn't found but it is needed?
It will not fail but I guess the usb host won't work as the clock won't be correctly

I agree with you: this is not a good solution.

Another option is to keep the previous version of this patch and put uclk handling
in "#ifdef CONFIG_COMMON_CLK #endif" sections.

Would this be acceptable ?

Alan Stern

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