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Date:   Mon, 31 Oct 2022 12:24:35 -0700
From:   Asutosh Das <quic_asutoshd@quicinc.com>
To:     Bart Van Assche <bvanassche@acm.org>
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Subject: Re: [PATCH v3 07/17] ufs: core: mcq: Calculate queue depth
Message-ID: <20221031192435.GD9077@asutoshd-linux1.qualcomm.com>
References: <cover.1666288432.git.quic_asutoshd@quicinc.com>
 <1987fbada1d33c04c9598614ef712e0a48fe065e.1666288432.git.quic_asutoshd@quicinc.com>
 <0fb3f8ae-5ed7-9057-0d2b-8866f36c2441@acm.org>
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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