[U-Boot] [PATCH] fdt: Do not report bad cell count when #size-cells = <0>

[Michal Simek]

On 14.4.2016 11:45, Przemyslaw Marczak wrote:
> Hello Michal,
> 
> +CC Stephen Warren
> 
> On 04/14/2016 08:20 AM, Michal Simek wrote:
>> Upcomming pca953x gpio driver (tca6416 is compatible with it)
>> is using for example this DT description (ZynqMP zcu102):
>> i2c0: i2c at ff020000 {
>>     compatible = "cdns,i2c-r1p10";
>>     interrupt-parent = <&gic>;
>>     interrupts = <0 17 4>;
>>     reg = <0x0 0xff020000 0x1000>;
>>     #address-cells = <1>;
>>     #size-cells = <0>;
>>
>>     tca6416_u61: gpio at 21 {
>>         compatible = "ti,tca6416";
>>         reg = <0x21>;
>>         gpio-controller;
>>         #gpio-cells = <2>;
>>     };
>> };
>>
>> I2C bus is using #size-cells = <0> which current code detects as
>> "Bad cell count":
>> OF: reached root node
>> OF: ** translation for device gpio at 20 **
>> __of_translate_address: Bad cell count for gpio at 20
>> Command 'gpio' failed: Error -19
>>
>> This patch fixes OF_CHECK_COUNTS macro not to report problem when
>> size-cells is 0 which is also valid bus configuration.
>>
>> Signed-off-by: Michal Simek <michal.simek at xilinx.com>
>> ---
>>
>>   common/fdt_support.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/common/fdt_support.c b/common/fdt_support.c
>> index ced119e70d9f..5f5b49c6210b 100644
>> --- a/common/fdt_support.c
>> +++ b/common/fdt_support.c
>> @@ -941,7 +941,7 @@ void fdt_del_node_and_alias(void *blob, const char
>> *alias)
>>   #define OF_MAX_ADDR_CELLS    4
>>   #define OF_BAD_ADDR    FDT_ADDR_T_NONE
>>   #define OF_CHECK_COUNTS(na, ns)    ((na) > 0 && (na) <=
>> OF_MAX_ADDR_CELLS && \
>> -            (ns) > 0)
>> +            (ns) >= 0)
>>
>>   /* Debug utility */
>>   #ifdef DEBUG
>>
> 
> Some time ago I tried to solve GPIO issue on Exynos boards, by proposing
> change similar to your patch. After some discussion with Stephen Warren
> and Simon Glass, I was aware, that it was a wrong approach to solve this
> problem.
> 
> You can follow it here:
> 
> http://comments.gmane.org/gmane.comp.boot-loaders.u-boot/247651
> 
> https://patchwork.ozlabs.org/patch/564246/
> https://patchwork.ozlabs.org/patch/557008/
> https://patchwork.ozlabs.org/patch/557010/
> https://patchwork.ozlabs.org/patch/557009/
> 
> As a conclusion, for MMIO addresses we are using 'reg' property with a
> range. If you need use this as I2C address or I2C device's register -
> e.g. 'reg = <0x4>' - it's good until you don't use dev_get_addr()
> function to get it - because it's a different address space - non-MMIO.
> 
> I didn't saw your GPIO driver, but I can assume, that you should use
> fdtdec_get_int() to get the GPIO register addres instead of dev_get_addr().
> 
> Please look at function i2c_chip_ofdata_to_platdata() in i2c-uclass.c,
> the reg is taken by using fdtdec_get_int()...

Thank you so much for this. That explain it. Using fdtdec_get_int() is
not a problem.

Please ignore this patch.

Thanks,
Michal