linux-kernel - Re: [PATCH] pwm: lp3943: Dynamically allocate pwm chip base

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Message-ID: <d1c0467a-f64e-fac5-54fa-e62ac8c5f448@ti.com>
Date:   Mon, 2 Nov 2020 10:31:42 +0530
From:   Lokesh Vutla <lokeshvutla@...com>
To:     Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
CC:     Thierry Reding <thierry.reding@...il.com>,
        Lee Jones <lee.jones@...aro.org>, <linux-pwm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Sekhar Nori <nsekhar@...com>
Subject: Re: [PATCH] pwm: lp3943: Dynamically allocate pwm chip base

Hi Uwe,

On 31/10/20 1:41 am, Uwe Kleine-König wrote:
> On Fri, Oct 30, 2020 at 07:11:35PM +0530, Lokesh Vutla wrote:
>> When there are other pwm controllers enabled along with pwm-lp3943,
>> pwm-lp3942 is failing to probe with -EEXIST error. This is because
>> other pwm controller is probed first and assigned pwmchip 0 and
>> pwm-lp3943 is requesting for 0 again. In order to avoid this, assign the
>> chip base with -1, so that id is dynamically allocated.
>>
>> Fixes: af66b3c0934e ("pwm: Add LP3943 PWM driver")
>> Signed-off-by: Lokesh Vutla <lokeshvutla@...com>
> 
> Reviewed-by: Uwe Kleine-König <u.kleine-könig@...gutronix.de>

Thanks.

> 
> With this patch applied only the pwm-ab8500 driver is left not using -1
> for base.

pwm-ab8500 is assigning ab8500->chip.base as pdev->id. At least in the DT case
pdev->id is always -1(as of today). So, base is being allocated dynamically in
case of DT.

Thanks and regards,
Lokesh

> 
> Best regards
> Uwe
>