Re: [RFC PATCH v2 1/2] scsi: ufs: Add Multi-Circular Queue support

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 8/24/22 18:42, Asutosh Das (asd) wrote:
On 8/18/2022 7:41 PM, Bart Van Assche wrote:
On 8/11/22 03:33, Can Guo wrote:
+static inline void ufshcd_mcq_process_event(struct ufs_hba *hba,
+                        struct ufs_hw_queue *hwq)
+{
+    struct cq_entry *cqe = ufshcd_mcq_cur_cqe(hwq);
+    int tag;
+
+    tag = ufshcd_mcq_get_tag(hba, hwq, cqe);
+    ufshcd_compl_one_task(hba, tag, cqe);
+}

Consider changing "process_event" into "process_cqe". Consider renaming ufshcd_compl_one_task() into ufshcd_compl_one_cqe().

The preparatory patch that would precede this change would define ufshcd_compl_one_task() in ufshcd.c. Since this function would be invoked both from Single Doorbell mode and MCQ mode, ufshcd_compl_one_task() sounds more relevant. What say?

The name "task" is confusing since in SCSI standard documents it refers to "task management" while ufshcd_compl_one_task() is not related to SCSI task management at all. So I would appreciate it if another name is chosen than ufshcd_compl_one_task().

+static irqreturn_t ufshcd_handle_mcq_cq_events(struct ufs_hba *hba)
+{
+    struct ufs_hw_queue *hwq;
+    unsigned long outstanding_cqs;
+    unsigned int nr_queues;
+    int i, ret;
+    u32 events;
+
+    ret = ufshcd_vops_get_outstanding_cqs(hba, &outstanding_cqs);
+    if (ret)
+        outstanding_cqs = (1U << hba->nr_hw_queues) - 1;
+
+    /* Exclude the poll queues */
+    nr_queues = hba->nr_hw_queues - hba->nr_queues[HCTX_TYPE_POLL];
+    for_each_set_bit(i, &outstanding_cqs, nr_queues) {
+        hwq = &hba->uhq[i];
+
+        events = ufshcd_mcq_read_cqis(hba, i);
+        if (events)
+            ufshcd_mcq_write_cqis(hba, events, i);
+
+        if (events & UFSHCD_MCQ_CQIS_TEPS)
+            ufshcd_mcq_poll_cqe_nolock(hba, hwq);
+    }
+
+    return IRQ_HANDLED;
+}

Why the loop over the completion queues? Shouldn't UFSHCI 4.0 compliant controllers support one interrupt per completion queue?

MCQ specification doesn't define that UFSHCI 4.0 compliant HC should support one interrupt per completion queue. I guess it would depend on HC vendors. But it specifies ESI as an alternate method; which is implemented in this patch.

It is unfortunate that support for the ESI mechanism is optional in the UFSHCI 4.0 specification since I consider this as one of the most important UFSHCI 4.0 features. I wouldn't mind if MCQ would only be supported for UFSHCI 4.0 controllers that support ESI.

+    if (hba->nutrs != old_nutrs) {
+        ufshcd_release_sdb_queue(hba, old_nutrs);
+        ret = ufshcd_memory_alloc(hba);
+        if (ret)
+            return ret;
+        ufshcd_host_memory_configure(hba);
+    }

Can this freeing + reallocating be avoided?

Umm, we thought about this. Only after reading the device params, the ext_iid support and the device queue depth be determined. So didn't look like there's any other way than this. If you have any ideas, please let us know.




[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [SCSI Target Devel]     [Linux SCSI Target Infrastructure]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Linux IIO]     [Samba]     [Device Mapper]

  Powered by Linux