linux-kernel - Re: [PATCH 1/2] i2c: exynos5: support USI(Universal Serial Interface)

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Date:   Thu, 4 Nov 2021 11:41:47 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Jaewon Kim <jaewon02.kim@...sung.com>,
        'Wolfram Sang' <wsa@...nel.org>,
        'Rob Herring' <robh+dt@...nel.org>
Cc:     'Chanho Park' <chanho61.park@...sung.com>,
        linux-i2c@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] i2c: exynos5: support USI(Universal Serial Interface)

On 04/11/2021 09:10, Jaewon Kim wrote:
> 
>>> +	if (ret) {
>>> +		dev_err(dev, "usi-sysreg offset is not specified\n");
>>> +		return ret;
>>> +	}
>>> +
>>> +	regmap_update_bits(i2c->usi_sysreg, i2c->usi_offset,
>>> +			SYSREG_USI_SW_CONF_MASK, SYSREG_I2C_SW_CONF);
>>> +
>>> +	exynos_usi_reset(i2c);
>>
>> You are clearing the reset flag, but not setting it back on probe failure. What happens if the probe
>> fails after this clear()? E.g.
>> because of deferred probe? The next probe try will start on a not-reset controller. Will it work?
>>
> 
> The user manual guides USI_RESET to be done after changing the system register.
> For clarity, we will change not only to clear reset, but to clear after reset.
> 

What I meant, is do you handle probe failure correctly (e.g. probe
deferral)? It's fine to leave the reset cleared after deferred probe?

Best regards,
Krzysztof