Re: [PATCH 2/5] usb: gadget: s3c-hsotg: support configurable UTMI PHY width

[Matt Porter <matt.porter@linaro.org>]

On 10/10/2013 11:29 AM, Felipe Balbi wrote:
> On Mon, Oct 07, 2013 at 06:12:29AM -0400, Matt Porter wrote:
>> Extend dwc2 binding with an optional utmi phy width property.
>> Enable the s3c-hsotg.c driver to use standard dwc2 binding
>> and enable configuration of the UTMI phy width based on the
>> property.
>>
>> Signed-off-by: Matt Porter <matt.porter@linaro.org>
>> Reviewed-by: Markus Mayer <markus.mayer@linaro.org>
>> Reviewed-by: Tim Kryger <tim.kryger@linaro.org>
>> ---
>>   Documentation/devicetree/bindings/staging/dwc2.txt |  4 ++++
>>   drivers/usb/gadget/s3c-hsotg.c                     | 18 +++++++++++++++++-
>>   drivers/usb/gadget/s3c-hsotg.h                     |  1 +
>>   3 files changed, 22 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/staging/dwc2.txt b/Documentation/devicetree/bindings/staging/dwc2.txt
>> index 1a1b7cf..fb6b8ee 100644
>> --- a/Documentation/devicetree/bindings/staging/dwc2.txt
>> +++ b/Documentation/devicetree/bindings/staging/dwc2.txt
>> @@ -6,10 +6,14 @@ Required properties:
>>   - reg : Should contain 1 register range (address and length)
>>   - interrupts : Should contain 1 interrupt
>>
>> +Optional properties:
>> +- snps,phy-utmi-width: Must contain the UTMI data width (either 8 or 16)
>
> isn't this available in any of the configuration registers ?

Yes and no. HWCFG4 has a UTMI data width field. However, it has 3 valid 
states, "8", "16", or "8 or 16". The BCM281xx implementation is set to 
the latter and the attached phy is 8-bit.

Looking at dwc2 prior to Matthijs Kooijman's patch [1] which starts 
validating the value of phy_utmi_width in that driver, the pci.c 
dwc2_module_params .phy_utmi_width field there even had the comment, "/* 
16 bits - NOT DETECTABLE */". The autodetect code in 
dwc2_set_param_phy_utmi_width() will fail if HWCFG4 has the "8 or 16" 
option as it just decides to default to a phy width of 16 if nothing is 
configured by the platform glue. This property would also allow this 
issue to be addressed in that driver.

>>   Example:
>>
>>           usb@101c0000 {
>>                   compatible = "ralink,rt3050-usb, snps,dwc2";
>>                   reg = <0x101c0000 40000>;
>>                   interrupts = <18>;
>> +		snps,phy-utmi-width = <8>;
>
> indentation.

will fix.

-Matt

[1] de4a193 staging: dwc2: validate the value for phy_utmi_width