[PATCH v8 4/9] davinci: McASP configuration for Omapl138-Hawkboard

[Victor Rodriguez]

On Tue, Nov 16, 2010 at 2:42 PM, Michael Williamson
<michael.williamson at criticallink.com> wrote:
> On 11/16/2010 11:37 AM, Nori, Sekhar wrote:
>
>> On Tue, Nov 16, 2010 at 21:34:03, Sergei Shtylyov wrote:
>>
>>>
>>>> HI Sergei and Sekhar
>>>
>>>> Thanks for check the patch
>>>
>>>> What I can do if you agree with this change is to leave da850.c as it
>>>> is,
>>>
>>>     No, please don't.
>>>
>>>> and declare
>>>
>>>> static short hawk_mcasp_pins[] __initdata = {
>>>>     DA850_AHCLKX, DA850_ACLKX, DA850_AFSX,
>>>>     DA850_AHCLKR, DA850_ACLKR, DA850_AFSR, DA850_AMUTE,
>>>>     DA850_AXR_11, DA850_AXR_12, DA850_AXR_13, DA850_AXR_14,
>>>>     -1
>>>> };
>>>
>>>> on the hawkboard file and call it insted of da850_mcasp_pins.
>>>
>>>>     ret = davinci_cfg_reg_list(hawk_mcasp_pins);
>>>>     if (ret)
>>>>             pr_warning("%s: mcasp mux setup failed: %d\n", __func__, ret);
>>>
>>>> Please tell me if you agree with this change, I think is better
>>>> because I do not touch any other file besides my board file.
>>>
>>>     No, it's not really better. The generic list in da850.c should be more
>>> complete, regardless... Ideally, you should go thru the DA850 manual and put in
>>> that list all McASP pins that aren't already there. Then you can use your own
>>> pin list if that *complete* pin list can't be used on your board.
>>
>> That will cause a bunch of pin conflicts on the EVM so it will need
>> its own list too.
>>
>
>
> Help me out.  Why do we need generic pin lists?
>
> It seems to me that the "generic pin list" for da850.c isn't practical for most
> (if not all) of the peripherals.  They should be done using __initdata in
> each board file.
>
> Just a cursory glance at what's in da850.c highlights several items being set
> up for the EVM and not generically.  For example:
>
> - da850_uart1_pins and da850_uart2_pins: I believe both have RTS/CTS pins which
>  for a generic definition should be included as for UART0, but would then
>  be unused as the EVM doesn't use these pins in this function.
>
> - da850_mcasp_pins: if generic, must include all 16 AXR pins.  I think you'd
>  be hard pressed to find a board configuration that would use all 16 AXR pins
>  for the McASP.  I'm fairly sure the EVM uses the pins called out, and uses
>  other pins for other functions.  So it's likely this structure wouldn't get used.
>
> - da850_mmcsd0_pins : includes 2 GPIO pins (specific to the EVM, though possible for
>  other boards) for the card detect and write protect signals.  These pins are
>  completely arbitrary for that particular board design. I also believe that
>  the complete mmcsd0 port has 4 more data lines as part of it's peripheral, although
>  the driver doesn't support using them.
>
> - da850_emif25_pins interface doesn't include the generic pins for some of
>  the SDRAM functions.
>
> - da850_cpgmac_pins defines both RMII and MII pins.  I don't think any board
>  would want to configure both sets at the same time.  Seems like this should
>  never get used...
>
> It's also incomplete.  What about the uPP pin list?  Or the VPIF?  Etc.
>
> I think a board file author should be familiar enough with the SoC to understand
> what peripheral pins he should be configuring for his/her particular hardware setup
> and explicitly specify them in the board file.
>
> If you remove the common pin-mux lists and move them to a board file, then once you
> configure your specific platform, is there any more memory used than with
> the common scheme?  Of course, there would be replication of pin-mux code in the board
> files that had identical configurations.  Is that the driver for the current implementation?
>
> Is there a thread that hashes through the decisions on this that I should be googling?
>
> Thanks for any insight.
>
> -Mike
>
>
>
>
>
>
>


Hi Mike thanks for the comments I agree with the part of replication

So do you recommend that the best way to solve this problem is to make
a  pin list that has all the 16 pins on da850.c ?

I have checked and on the file

arch/arm/mach-davinci/include/mach/mux.h

are declared

        /* McASP function */
        DA850_ACLKR,
        DA850_ACLKX,
        DA850_AFSR,
        DA850_AFSX,
        DA850_AHCLKR,
        DA850_AHCLKX,
        DA850_AMUTE,
        DA850_AXR_15,
        DA850_AXR_14,
        DA850_AXR_13,
        DA850_AXR_12,
        DA850_AXR_11,
        DA850_AXR_10,
        DA850_AXR_9,
        DA850_AXR_8,
        DA850_AXR_7,
        DA850_AXR_6,
        DA850_AXR_5,
        DA850_AXR_4,
        DA850_AXR_3,
        DA850_AXR_2,
        DA850_AXR_1,
        DA850_AXR_0,

I have changed the pin list to


const short da850_mcasp_pins[] __initdata = {
        DA850_AHCLKX, DA850_ACLKX, DA850_AFSX,
        DA850_AHCLKR, DA850_ACLKR, DA850_AFSR, DA850_AMUTE,
        DA850_AXR_11, DA850_AXR_12,DA850_AXR_13, DA850_AXR_14, DA850_AXR_15,
        -1
};

and after checked with the hawk board it works fine

I have put on the list all the available pins for McASP even if
hawkboard does not need the last one DA850_AXR_15 , and is still
working

Please tell me which way do you recommend me

Regards

Victor Rodriguez