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

[Marek Vasut]

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 ...

-- 
Best regards,
Marek Vasut