[U-Boot] [PATCH v2] DW SPI: Get clock value from Device Tree

[Marek Vasut]

On 10/24/2017 11:52 AM, Jagan Teki wrote:
> On Tue, Oct 24, 2017 at 11:38 AM, Marek Vasut <marex at denx.de> wrote:
>> On 10/23/2017 01:43 PM, Eugeniy Paltsev wrote:
>>> On Thu, 2017-10-19 at 13:20 -0500, Dinh Nguyen wrote:
>>>>
>>>> On 10/19/2017 10:51 AM, Marek Vasut wrote:
>>>>> On 10/19/2017 05:36 PM, Eugeniy Paltsev wrote:
>>>>>> On Tue, 2017-10-17 at 20:32 +0530, Jagan Teki wrote:
>>>>>>> On Tue, Oct 17, 2017 at 8:27 PM, Alexey Brodkin
>>>>>>> <Alexey.Brodkin at synopsys.com> wrote:
>>>>>>>> Hi Jagan,
>>>>>>>>
>>>>>>>>> -----Original Message-----
>>>>>>>>> From: Eugeniy Paltsev [mailto:paltsev at synopsys.com]
>>>>>>>>> Sent: Tuesday, October 17, 2017 4:33 PM
>>>>>>>>> To: jagannadh.teki at gmail.com
>>>>>>>>> Cc: u-boot at lists.denx.de; uboot-snps-arc at synopsys.com
>>>>>>>>> Subject: [uboot-snps-arc] Re: [PATCH v2] DW SPI: Get clock value from Device Tree
>>>>>>>>>>
>>>>>>>>>> How hard it is to make others to use clock manager? do you have any list?
>>>>>>>>>
>>>>>>>>> clock_manager.h is an old (and non-generic) way to deal with different clocks.
>>>>>>>>> For example in SOCFPGA_GEN5 and SOCFPGA_ARRIA10 clock_manager.h provides
>>>>>>>>> cm_get_spi_controller_clk_hz function to deal with spi controller clock.
>>>>>>>>>
>>>>>>>>> But today we have another, linux-like alternative: to bind clocks via device tree
>>>>>>>>> and manipulate with clocks via generic functions provided by clk.h
>>>>>>>>>
>>>>>>>>> In this patch I added option to get clock via device tree using standard bindings
>>>>>>>>> and restrict clock_manager.h functions usage only to targets which still use it,
>>>>>>>>> so new targets can simply bind clock via device tree and they do not need to
>>>>>>>>> implement/define something in clock_manager.h
>>>>>>>>>
>>>>>>>>> So we don't need to make others to use clock manager :)
>>>>>>>>
>>>>>>>> Maybe it worth trying the other way around and think about switching SOCFPGA platforms to
>>>>>>>> generic clk framework?
>>>>>>>
>>>>>>> Yes, ie what exactly I thought of, thanks!
>>>>>>
>>>>>> I checked cm_get_spi_controller_clk_hz implementation in SOCFPGA_GEN5 and
>>>>>> SOCFPGA_ARRIA10: we can't simply replace it with "fixed-clock" driver as it
>>>>>> manipulate with real hardware.
>>>>>> The only way to do it is to replace SOCFPGA* clock manager functions by real
>>>>>> clock driver.
>>>>>>
>>>>>> And given I don't have mentioned hardware so I barely can help with
>>>>>> those improvements on SOCFPGA. That said if there're no short-term plans to
>>>>>> switch SOCFPGA to clk framework maybe we'll be OK with my workaround with #ifdefs?
>>>>>
>>>>> Wait for Dinh's reply ...
>>>>>
>>>>
>>>> Honestly, I don't have too much time to work on this right now. So I
>>>> really don't when it can get done. But it'll go on my to-do list.
>>>>
>>>> Dinh
>>>
>>> Yep, thanks for your comments.
>>>
>>> So, Jagan,
>>> given Dinh's reply, could you please apply this patch?
>>
>> I'd really hate it to start seeing soc-specific ifdefs in drivers,
>> that's IMO not acceptable. A __weak override might be a temporary
>> solution I'd be willing to live with though.
> 
> I would rather like to see some check on clock manager itself whether
> CONFIG_IS_ENABLED(CLK) is using or not? this can tends not to use
> __weak as well soc #ifdefs in driver.

I don't understand what you mean by this , can you elucidate ?

-- 
Best regards,
Marek Vasut