linux-kernel - Re: [PATCH 1/3] scsi: ufshcd: switch to a version macro

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Message-ID: <0c6cff2b-8d56-2b34-837d-b3d8f1fa5ad9@connolly.tech>
Date:   Mon, 08 Mar 2021 10:42:43 +0000
From:   Caleb Connolly <caleb@...nolly.tech>
To:     Christoph Hellwig <hch@....de>
Cc:     Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        ejb@...ux.ibm.com, stanley.chu@...iatek.com, cang@...eaurora.org,
        beanhuo@...ron.com, jaegeuk@...nel.org, asutoshd@...eaurora.org,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] scsi: ufshcd: switch to a version macro

Hi Christoph,

On 08/03/2021 8:00 am, Christoph Hellwig wrote:
> This looks like a really nice improvement!
>
> A bunch of comments below:
>
>> @@ -696,10 +685,21 @@ static inline u32 ufshcd_get_intr_mask(struct ufs_hba *hba)
>>    */
>>   static inline u32 ufshcd_get_ufs_version(struct ufs_hba *hba)
>>   {
>> +	u32 ufshci_ver;
> missing eempty line after the declaration.
>
>>   	if (hba->quirks & UFSHCD_QUIRK_BROKEN_UFS_HCI_VERSION)
>> +		ufshci_ver = ufshcd_vops_get_ufs_hci_version(hba);
>> +	else
>> +		ufshci_ver = ufshcd_readl(hba, REG_UFS_VERSION);
>>
>> +	/*
>> +	 * UFSHCI v1.x uses a different version scheme, in order
>> +	 * to allow the use of comparisons with the UFSHCI_VER
>> +	 * macro, we convert it to the same scheme as ufs 2.0+.
>> +	 */
>> +	if (ufshci_ver & 0x00010000)
>> +		ufshci_ver = UFSHCI_VER(1, ufshci_ver & 0x00000100);
>> +
>> +	return ufshci_ver;
> I'd use early returns here to clean this up a bit:
>
>   	if (hba->quirks & UFSHCD_QUIRK_BROKEN_UFS_HCI_VERSION)
> 		ufshci_ver = ufshcd_vops_get_ufs_hci_version(hba);
>
> 	...
> 	ufshci_ver = ufshcd_readl(hba, REG_UFS_VERSION);
> 	if (ufshci_ver & 0x00010000)
> 		return UFSHCI_VER(1, ufshci_ver & 0x00000100);
> 	return ufshci_ver;
>
>> +#define UFSHCI_VER(major, minor) \
>> +	((major << 8) + (minor << 4))
> This needs braces around major and minor.  Or better just convert it
> to an inline function (and use a lower case name).

Other (similar) implementations, like NVME_VS() use a macro here, is an 
inline function just personal preference?

I'm perfectly happy either way, so I'll switch to your suggestion.

Thanks for the review.

Regards,

Caleb