linux-kernel - Re: [PATCH v2 1/9] reset: amlogic: convert driver to regmap

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Message-ID: <1jr0bqmxdj.fsf@starbuckisacylon.baylibre.com>
Date: Thu, 18 Jul 2024 19:19:04 +0200
From: Jerome Brunet <jbrunet@...libre.com>
To: Neil Armstrong <neil.armstrong@...aro.org>
Cc: Philipp Zabel <p.zabel@...gutronix.de>,  Stephen Boyd
 <sboyd@...nel.org>,  Jan Dakinevich <jan.dakinevich@...utedevices.com>,
  linux-kernel@...r.kernel.org,  linux-amlogic@...ts.infradead.org,
  linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 1/9] reset: amlogic: convert driver to regmap

On Thu 18 Jul 2024 at 14:45, Neil Armstrong <neil.armstrong@...aro.org> wrote:

>> +
>>   static int meson_reset_reset(struct reset_controller_dev *rcdev,
>> -			      unsigned long id)
>> +			     unsigned long id)
>>   {
>>   	struct meson_reset *data =
>>   		container_of(rcdev, struct meson_reset, rcdev);
>> -	unsigned int bank = id / BITS_PER_REG;
>> -	unsigned int offset = id % BITS_PER_REG;
>> -	void __iomem *reg_addr = data->reg_base + (bank << 2);
>> +	unsigned int offset, bit;
>>   -	writel(BIT(offset), reg_addr);
>> +	meson_reset_offset_and_bit(data, id, &offset, &bit);
>>   -	return 0;
>> +	return regmap_update_bits(data->map, offset,
>> +				  BIT(bit), BIT(bit));
>
> Here, you're converting a:
> writel(BIT())
> to a:
> reg = readl()
> reg |= BIT()
> writel(reg)
>
> so indeed you should use regmap_write(data->map, offset, BIT(bit))
>

Ok the trouble is this particular register which is write only, not
some writel vs regmap problem. The read value is probably undefined.
I should not have changed which the migration anyway.

Thanks for pointing it out, I'll fix that in v3

-- 
Jerome