Re:Re: [PATCH v9 13/15] serial: 8250_dw: add Ambarella CV75 quirks

[Jerome Brunet <jbrunet@baylibre.com>]

On ven. 02 oct. 2026 at 10:17, zl020895  <zl020895@163.com> wrote:

> Hi Greg, Linus,
>
> Thanks.
>
> This series follows the new-vendor, new-SoC process and is sent
> as one set, so the new Kconfig symbol and the drivers that use it
> land together.

What Greg and Linus say here is basically what I already suggested on
v6 [1]

Giving the whole context of a bring ups, mixing many trees, might be
nice at the RFC stage but then it makes a lot more difficult.

[1]: https://lore.kernel.org/all/1jld986j7m.fsf@starbuckisacylon.baylibre.com/

>
> If it has to be split, the GPIO patches and the UART patches can
> go out as their own series. The SoC patches and the CV75 clock
> driver should stay in one series: the clock Kconfig depends on
> ARCH_AMBARELLA, which is added by the arm64 patch.
>
> Would that split be acceptable for you?
>

I don't get why clock is any different here. Just state your
dependencies in the cover letter. `b4` can help you there as well.

> Best regards,
> Long Zhao
>
> At 2026-10-02 03:20:51, "Linus Walleij" <linusw@kernel.org> wrote:
>>On Thu, Oct 1, 2026 at 2:52 PM Greg Kroah-Hartman
>><gregkh@linuxfoundation.org> wrote:
>>> On Thu, Oct 01, 2026 at 08:41:02PM +0800, Long Zhao via B4 Relay wrote:
>>
>>> > From: Long Zhao <longzhao@ambarella.com>
>>> >
>>> > The Ambarella CV75 UART is Ambarella IP, not a Synopsys DesignWare
>>> > licensed block. At the register level it is close enough to DW APB UART
>>> > that a full custom UART driver is unnecessary: reuse 8250_dw with a
>>> > small platform quirk.
>>> >
>>> > Quirks:
>>> > - keep IER ETOI (bit 5) set for RX timeout behaviour
>>> > - skip set_rate; baud clock is managed outside the UART block
>>> >
>>> > Reviewed-by: Linus Walleij <linusw@kernel.org>
>>> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>>> > Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
>>> > Signed-off-by: Long Zhao <longzhao@ambarella.com>
>>> > ---
>>> >  drivers/tty/serial/8250/8250_dw.c | 32 ++++++++++++++++++++++++++++++++
>>> >  1 file changed, 32 insertions(+)
>>>
>>> When you submit lots of different subsystem patches all in one series,
>>> it's hard, if not impossible, for subsystem maintainers to take them :(
>>
>>In my experience people do this in cases like this it is because they
>>essentially dump out their "bring-up" tree, the thing they have
>>booting on the hardware so they know the pieces work together.
>>
>>Long: can you split it up in topic branches and work on e.g. the
>>serial driver on a separate branch?
>>
>>A better way to test the whole set of patces is to just create a
>>mixdown branch where you merge all the topic branched into
>>one "test" branch, then you boot and test this before sending
>>out each branch separately.
>>
>>Each topic branch can be versioned separately with b4.
>>
>>Yours,
>>Linus Walleij

-- 
Jerome