Re: [PATCH v2] clk: i.MX: Port Linux clock tree for i.MX51 and i.MX53

[Andrey Smirnov <andrew.smirnov@gmail.com>]

On Thu, Sep 6, 2018 at 12:48 AM Sascha Hauer <s.hauer@pengutronix.de> wrote:
>
> On Wed, Aug 29, 2018 at 10:02:07PM -0700, Andrey Smirnov wrote:
> > Existing clock tree code for i.MX5 in Barebox predates DT and is not
> > aware of it. This results in missing clocks on DT-based boards like
> > RDU1 and Babbage. Port clock tree from Linux to resolve this
> > problem. Old non-DT clock code is kept around for the sake of the
> > boards that were never converted to use DT.
>
> Overall I am not happy with this patch.
>
> With this patch we now have two clock drivers for the i.MX5 - not only
> in the source tree but also in the binaries.
>
> Yesterday I tried fleshing out the differences between both drivers. I
> renamed "clks" to "clk", adjusted whitespaces, changed register defines
> to the pattern "#define MXC_CCM_xxx (ccm_base + 0x*)". What I got was
> quite a bit closer to the kernel driver but still not there. It revealed
> some bugs in the kernel driver though. There are several differences in
> the register layout between the i.MX50 and the i.MX51/53 (See
> IMX5_CLK_ESDHC_A_SEL for example, MXC_CCM_CSCMR1[20:21] on i.MX51/53 and
> MXC_CCM_CSCMR1[21:22] on the i.MX50). These are correctly abstracted
> in the current barebox driver but not in the Linux driver, see
> mx5_clocks_mx51_mx53_init() which doesn't exist in the Linux driver.
>
> So by switching to the Kernel clk driver we introduce a bunch of new
> bugs into barebox which of course is unfortunate.
>
> Finally your patch does not compile on some configs
> (efika-mx-smartbook_defconfig for example) since COMMON_CLK_OF_PROVIDER
> is not selected. That's rather simple to fix of course.
>
> Which clocks are you missing? Maybe it would be better to add the
> missing clocks to the barebox clock driver instead of adding a new one?
>

There's already a patch for that for original driver:
http://lists.infradead.org/pipermail/barebox/2018-August/034413.html
My hope was to use this as an opportunity to switch to using kernel
code, but if we don't really want to pay the price for that, then I
think Michael's patch should work just fine.

Also, just out of curiosity, are you planning to upstream the fixes
for bugs in kernel driver you found?

Thanks,
Andrey Smirnov

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