Re: [PATCH v2] phy: stm32-usphyc: add 200 to 300 us delay to fix timeout on some machines

From: Michael Grzeschik <mgr@pengutronix.de>
To: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-phy@lists.infradead.org, vkoul@kernel.org,
	kishon@kernel.org, mcoquelin.stm32@gmail.com,
	alexandre.torgue@foss.st.com, error27@gmail.com,
	kernel@pengutronix.de, linux-stm32@st-md-mailman.stormreply.com,
	amelie.delaunay@foss.st.com
Subject: Re: [PATCH v2] phy: stm32-usphyc: add 200 to 300 us delay to fix timeout on some machines
Date: Fri, 10 Mar 2023 11:44:38 +0100	[thread overview]
Message-ID: <20230310104438.GB7352@pengutronix.de> (raw)
In-Reply-To: <27b9e057-bdd7-b4e6-445c-8da700423600@foss.st.com>

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Hi Fabrice,

On Tue, Feb 28, 2023 at 06:28:21PM +0100, Fabrice Gasnier wrote:
>On 2/27/23 16:13, Michael Grzeschik wrote:
>> An minimum udelay of 200 us seems to be necessary on some machines. After
>> the setup of the pll, which needs about 100 us to be locked there seem
>> to be additional 100 us to get the phy really functional. Without this
>> delay the usb runs not functional. With this additional short udelay
>> this issue was not reported again.
>>
>> Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
>>
>
>Hi Michael,
>
>Thank you for the updates,
>
>Fell free to add my:
>Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>

Thanks!

Trhough which tree will this be picked?
Wil it be possible to add this to v6.3?

Regards,
Michael

>> ---
>> v1 -> v2: - changed the mdelay to udelay_range(200, 300), like suggested by fabrice
>>           - moved the delay to pll enable so it will only be triggered once
>>
>>  drivers/phy/st/phy-stm32-usbphyc.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/phy/st/phy-stm32-usbphyc.c b/drivers/phy/st/phy-stm32-usbphyc.c
>> index 5bb9647b078f12..dd469f57fba7eb 100644
>> --- a/drivers/phy/st/phy-stm32-usbphyc.c
>> +++ b/drivers/phy/st/phy-stm32-usbphyc.c
>> @@ -317,6 +317,9 @@ static int stm32_usbphyc_pll_enable(struct stm32_usbphyc *usbphyc)
>>
>>  	stm32_usbphyc_set_bits(pll_reg, PLLEN);
>>
>> +	/* Wait for maximum lock time */
>> +	usleep_range(200, 300);
>> +
>>  	return 0;
>>
>>  reg_disable:
>

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