linux-kernel - Re: [PATCH v5 2/4] soc: samsung: usi: add a routine for unconfiguring the ip

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Message-ID: <ea2db4a3-47d3-42d7-bd51-18a0c3eb6d42@kernel.org>
Date: Wed, 15 Jan 2025 09:24:58 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Ivaylo Ivanov <ivo.ivanov.ivanov1@...il.com>,
 Rob Herring <robh@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
 Alim Akhtar <alim.akhtar@...sung.com>,
 Sam Protsenko <semen.protsenko@...aro.org>,
 Peter Griffin <peter.griffin@...aro.org>
Cc: devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/4] soc: samsung: usi: add a routine for unconfiguring
 the ip

On 14/01/2025 22:57, Ivaylo Ivanov wrote:
> On 1/14/25 20:03, Krzysztof Kozlowski wrote:
>> On 09/01/2025 10:03, Ivaylo Ivanov wrote:
>>> +static void exynos_usi_unconfigure(void *data)
>>> +{
>>> +	struct exynos_usi *usi = data;
>>> +	u32 val;
>>> +
>>> +	/* Make sure that we've stopped providing the clock to USI IP */
>>> +	val = readl(usi->regs + USI_OPTION);
>>> +	val &= ~USI_OPTION_CLKREQ_ON;
>>> +	val |= ~USI_OPTION_CLKSTOP_ON;
>>> +	writel(val, usi->regs + USI_OPTION);
>>> +
>>> +	/* Set USI block state to reset */
>>> +	val = readl(usi->regs + USI_CON);
>>> +	val |= USI_CON_RESET;
>>> +	writel(val, usi->regs + USI_CON);
>> Also shouldn't you enable clocks for accessing these? They are being
>> disabled at the end of exynos_usi_enable().
> 
> Hm, perhaps. But I find that weird, since I haven't seen it in the downstream
> driver implementation.

So the downstream enables clocks when configured usi, but never when
unconfiguring? I could believe that no one cared about remove/error
paths, thus never tested.

Best regards,
Krzysztof