linux-kernel - Re: [PATCH 02/10] pwm: Add SI-EN SN3112 PWM support

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Message-ID: <bed21ca2-54c0-473d-b84b-2b404899a050@linaro.org>
Date: Thu, 25 Apr 2024 09:57:40 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Junhao Xie <bigfoot@...ssfun.cn>, Konrad Dybcio
 <konrad.dybcio@...aro.org>, wuxilin123@...il.com,
 Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Jessica Zhang
 <quic_jesszhan@...cinc.com>, Sam Ravnborg <sam@...nborg.org>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Bjorn Andersson <andersson@...nel.org>,
 Tengfei Fan <quic_tengfan@...cinc.com>,
 Molly Sophia <mollysophia379@...il.com>
Cc: linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 02/10] pwm: Add SI-EN SN3112 PWM support

On 25/04/2024 02:57, Junhao Xie wrote:
> On 2024/4/25 03:37, Konrad Dybcio wrote:
>> On 4/24/24 17:29, Xilin Wu via B4 Relay wrote:
>>> From: Junhao Xie <bigfoot@...ssfun.cn>
>>>
>>> Add a new driver for the SI-EN SN3112 12-channel 8-bit PWM LED controller.
>>>
>>> Signed-off-by: Junhao Xie <bigfoot@...ssfun.cn>
>>> ---
>> [...]
>>> +    return sn3112_write_reg(priv, SN3112_REG_PWM_EN + reg,
>>> +                priv->pwm_en_reg[reg]);
>>
>> This looks like a weird reimplementation of regmap_update_bits
>>
> 
> We cannot use regmap_update_bits because this chip does not support read command.
> It will discard all read command.

You could use regmap cache with all registers marked as cacheable, but not sure it's worth
doing this.

Neil

> 
>>> +}
>>> +
> [...]
>>
>> devm_pwmchip_add?
>>
>> Konrad
> 
> Thank you for your reply, I will fix them.
>