Re: [PATCH v3 07/17] ufs: core: mcq: Calculate queue depth

[Asutosh Das]

On Thu, Oct 27 2022 at 14:52 -0700, Bart Van Assche wrote:
> On 10/20/22 11:03, Asutosh Das wrote:
> > +u32 ufshcd_mcq_decide_queue_depth(struct ufs_hba *hba)
> > +{
> > +	u32 qd, val;
> > +	int mac;
> > +
> > +	mac = ufshcd_mcq_vops_get_hba_mac(hba);
> > +	if (mac < 0) {
> > +		val = ufshcd_readl(hba, REG_UFS_MCQ_CFG);
> > +		mac = FIELD_GET(MCQ_CFG_MAC_MASK, val);
> > +	}
>
> According to the UFSHCI 4.0 specification the MAC value is set by the 
> host. Can the above code read the MAC value from the host controller 
> before it has been set by the host? If so, how about leaving out the 
> code that reads the MAC value from the controller and making it 
> mandatory to implement the new get_hba_mac vop?
The reason it is not mandatory to define get_hba_mac vop is UFSHCI 4.0
specification mentions that the default value of MAC is 32. So even if a vendor
HC doesn't override the MAC, it'd be 32.
Hence, the current code first checks for an override, and if there's none uses
the default value defined in the HC.

-asd