linux-kernel - Re: [PATCH v2 3/3] scsi: ufs: rockchip: init support for UFS

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Message-ID: <4de61c50-0f84-40b6-8993-d4e82cf54be0@kernel.org>
Date: Fri, 9 Aug 2024 07:44:01 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Shawn Lin <shawn.lin@...k-chips.com>, Rob Herring <robh+dt@...nel.org>,
 "James E . J . Bottomley" <James.Bottomley@...senPartnership.com>,
 "Martin K . Petersen" <martin.petersen@...cle.com>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
 Heiko Stuebner <heiko@...ech.de>, Alim Akhtar <alim.akhtar@...sung.com>,
 Avri Altman <avri.altman@....com>, Bart Van Assche <bvanassche@....org>,
 YiFeng Zhao <zyf@...k-chips.com>, Liang Chen <cl@...k-chips.com>,
 linux-scsi@...r.kernel.org, linux-rockchip@...ts.infradead.org,
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 3/3] scsi: ufs: rockchip: init support for UFS

On 09/08/2024 02:53, Shawn Lin wrote:
> 在 2024/8/8 18:36, Krzysztof Kozlowski 写道:
>> On 08/08/2024 05:52, Shawn Lin wrote:
>>> RK3576 contains a UFS controller, add init support fot it.
>>>
>>> Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
>>>
>>
>> ...
>>
>>> +	err = clk_prepare_enable(host->ref_out_clk);
>>> +	if (err)
>>> +		return dev_err_probe(dev, err, "failed to enable ref out clock\n");
>>> +
>>> +	host->rst_gpio = devm_gpiod_get(&pdev->dev, "reset", GPIOD_OUT_LOW);
>>> +	if (IS_ERR(host->rst_gpio)) {
>>> +		dev_err_probe(&pdev->dev, PTR_ERR(host->rst_gpio),
>>> +				"invalid reset-gpios property in node\n");
>>> +		err = PTR_ERR(host->rst_gpio);
>>
>> No. Look at your code above - you have return dev_err_probe, so logical
>> is that the syntax is err = dev_err_probe. Don't over-complicate the code.
>>
>> Anyway, this is suspicious. You already have resets with four resets
>> (!!!) and you claim you have fifth reset - GPIO? This looks just wrong,
>> like you represent some properties which do not belong here.
>>
> 
> Thanks for the feadback.
> 
> Yes, we have 4 resets for controller, and one gpio to reset the
> device. It happened to be called reset-gpios in DT but can be
> any name if you like it to be. I added reset-gpios as a required one
> listed in dt-bindings file, in patch 2.

Then explain in the bindings what this reset-gpios is for.
> 
> 
>  > Also, why do you leave the device in the reset state? Logical one
> means
>  > - reset is asserted. This applies to ufs_rockchip_device_reset() as > 
> well
>  > - that's just wrong code.
> 
> 
> No, I tested it in linux-net and the output is HIGH, and leave the
> device in active state.
> 
> In dts, we add:
> reset-gpios = <&gpio4 RK_PD0 GPIO_ACTIVE_HIGH>;

? Don't use random values, what is type of the reset line?

> 
> so gpiod_set_value_cansleep(host->rst_gpio, 1) -> output HIGH for
> gpio4_d0. Based on your comment, we should change the dts to use
> GPIO_ACTIVE_LOW and then gpiod_set_value_cansleep（host->rst_gpio, 0）
> 
> 
> Both can work, however IMO, isn't logical one means HIGH level in line 
> more human readable?

You mix logical level and line level.

If this is reset GPIO, then 1 means asserted so your code is bogus.

Maybe the the line is active low?

> 
> 
> 
>> Where is your DTS so we can validate it?
>>
> 
> Will add it in the next version, as now the rk3576.dtsi is under
> reviewed and UFS node was not added. So I was afraid to interfere
> with that patch and just wanted to add incremental patch once
> rk3576.dtsi got merged.
> 
>> Best regards,
>> Krzysztof
>>

Best regards,
Krzysztof