Re: [PATCH v1 2/3] clk: tegra: ignore unused vfir clock shared with uartb

From: Marcel Ziswiler
Date: Mon Dec 10 2018 - 16:41:46 EST

On November 28, 2018 10:24:04 AM GMT+01:00, Thierry Reding <thierry.reding@xxxxxxxxx> wrote:
>On Thu, Nov 01, 2018 at 10:41:52AM +0200, Peter De Schrijver wrote:
>> On Thu, Nov 01, 2018 at 02:52:29AM +0100, Marcel Ziswiler wrote:
>> > From: Marcel Ziswiler <marcel.ziswiler@xxxxxxxxxxx>
>> >
>> > As UARTB and VFIR share their clock enable bit it is rather unwise
>> > the kernel to turn off the VFIR one should that be unused (and
>> > potentially vice versa but so far there anyway is no VFIR driver).
>> >
>> > Without this patch trying to use UARTB with the regular 8250 driver
>> > will freeze as soon as ttyS1 is accessed after boot. Luckily, using
>> > high-speed Tegra serial driver won't exhibit the issue as clocks
>> > dynamically enabled/disabled on every access.
>> >
>> > This has been reproduced both on Apalis T30 as well as Apalis TK1
>> > may be an issue on all Tegra UARTB's which share the clock enable
>> > VFIR.
>> >
>> Ah.. the correct fix for this is to initialize the enable_refcnt
>based on the
>> hw state. This is done in 9619dba8325fce098bbc9ee2911d1b0150fec0c9
>> periph gate clocks, but obviously also applies to normal periph
>Hi Marcel,
>were you going to send a new version with the alternative fix as
>suggested by Peter?

Yes, sorry. Let me look at that now.