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Commit c2e09426 authored by Sultan Alsawaf's avatar Sultan Alsawaf Committed by Pranav Vashi
Browse files

scsi: ufs: Add simple IRQ-affined PM QoS operations 



Qualcomm's PM QoS solution suffers from a number of issues: applying
PM QoS to all CPUs, convoluted spaghetti code that wastes CPU cycles,
and keeping PM QoS applied for 10 ms after all requests finish
processing.

This implements a simple IRQ-affined PM QoS mechanism for each UFS
adapter which uses atomics to elide locking, and enqueues a worker to
apply PM QoS to the target CPU as soon as a command request is issued.

Change-Id: I634873deb7baf0916208809c025eb0d3ccdb0fa3
Signed-off-by: default avatarSultan Alsawaf <sultan@kerneltoast.com>
Signed-off-by: default avatarAlexander Winkowski <dereference23@outlook.com>
Signed-off-by: default avatarPranav Vashi <neobuddy89@gmail.com>
parent 215db380

drivers/scsi/ufs/ufshcd.c

+82 −4
Original line number Diff line number Diff line
@@ -3745,6 +3745,48 @@ static inline void ufshcd_put_read_lock(struct ufs_hba *hba) 
	up_read(&hba->lock);

}



static void ufshcd_pm_qos_get_worker(struct work_struct *work)

{

	struct ufs_hba *hba = container_of(work, typeof(*hba), pm_qos.get_work);



	if (!atomic_read(&hba->pm_qos.count))

		return;



	mutex_lock(&hba->pm_qos.lock);

	if (atomic_read(&hba->pm_qos.count) && !hba->pm_qos.active) {

		pm_qos_update_request(&hba->pm_qos.req, 100);

		hba->pm_qos.active = true;

	}

	mutex_unlock(&hba->pm_qos.lock);

}



static void ufshcd_pm_qos_put_worker(struct work_struct *work)

{

	struct ufs_hba *hba = container_of(work, typeof(*hba), pm_qos.put_work);



	if (atomic_read(&hba->pm_qos.count))

		return;



	mutex_lock(&hba->pm_qos.lock);

	if (!atomic_read(&hba->pm_qos.count) && hba->pm_qos.active) {

		pm_qos_update_request(&hba->pm_qos.req, PM_QOS_DEFAULT_VALUE);

		hba->pm_qos.active = false;

	}

	mutex_unlock(&hba->pm_qos.lock);

}



static void ufshcd_pm_qos_get(struct ufs_hba *hba)

{

	if (atomic_inc_return(&hba->pm_qos.count) == 1)

		queue_work(system_unbound_wq, &hba->pm_qos.get_work);

}



static void ufshcd_pm_qos_put(struct ufs_hba *hba)

{

	if (atomic_dec_return(&hba->pm_qos.count) == 0)

		queue_work(system_unbound_wq, &hba->pm_qos.put_work);

}



/**

 * ufshcd_queuecommand - main entry point for SCSI requests

 * @cmd: command from SCSI Midlayer
@@ -3760,12 +3802,16 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd) 
	int tag;

	int err = 0;

	bool has_read_lock = false;

	bool cmd_sent = false;



	hba = shost_priv(host);



	if (!cmd || !cmd->request || !hba)

		return -EINVAL;



	/* Wake the CPU managing the IRQ as soon as possible */

	ufshcd_pm_qos_get(hba);



	tag = cmd->request->tag;

	if (!ufshcd_valid_tag(hba, tag)) {

		dev_err(hba->dev,
@@ -3777,10 +3823,13 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd) 
	err = ufshcd_get_read_lock(hba, cmd->device->lun);

	if (unlikely(err < 0)) {

		if (err == -EPERM) {

			return SCSI_MLQUEUE_HOST_BUSY;

			err = SCSI_MLQUEUE_HOST_BUSY;

			goto out_pm_qos;

		}

		if (err == -EAGAIN) {

			err = SCSI_MLQUEUE_HOST_BUSY;

			goto out_pm_qos;

		}

		if (err == -EAGAIN)

			return SCSI_MLQUEUE_HOST_BUSY;

	} else if (err == 1) {

		has_read_lock = true;

	}
@@ -3937,16 +3986,22 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd) 
			if (has_read_lock)

				ufshcd_put_read_lock(hba);

			cmd->scsi_done(cmd);

			return 0;

			err = 0;

			goto out_pm_qos;

		}

		goto out;

	}



	cmd_sent = true;



out_unlock:

	spin_unlock_irqrestore(hba->host->host_lock, flags);

out:

	if (has_read_lock)

		ufshcd_put_read_lock(hba);

out_pm_qos:

	if (!cmd_sent)

		ufshcd_pm_qos_put(hba);

	return err;

}
@@ -6509,6 +6564,9 @@ static void __ufshcd_transfer_req_compl(struct ufs_hba *hba, 
			/* Mark completed command as NULL in LRB */

			lrbp->cmd = NULL;

			hba->ufs_stats.clk_rel.ctx = XFR_REQ_COMPL;

			if (cmd->request) {

				ufshcd_pm_qos_put(hba);

			}



			req = cmd->request;

			if (req) {
@@ -6585,6 +6643,14 @@ void ufshcd_abort_outstanding_transfer_requests(struct ufs_hba *hba, int result) 
			update_req_stats(hba, lrbp);

			/* Mark completed command as NULL in LRB */

			lrbp->cmd = NULL;

			if (cmd->request) {

				/*

				 * As we are accessing the "request" structure,

				 * this must be called before calling

				 * ->scsi_done() callback.

				 */

				ufshcd_pm_qos_put(hba);

			}

			clear_bit_unlock(index, &hba->lrb_in_use);

			ufshcd_release_all(hba);
@@ -11120,6 +11186,9 @@ void ufshcd_remove(struct ufs_hba *hba) 
	/* disable interrupts */

	ufshcd_disable_intr(hba, hba->intr_mask);

	ufshcd_hba_stop(hba, true);

	cancel_work_sync(&hba->pm_qos.put_work);

	cancel_work_sync(&hba->pm_qos.get_work);

	pm_qos_remove_request(&hba->pm_qos.req);



	ufshcd_exit_clk_gating(hba);

	ufshcd_exit_hibern8_on_idle(hba);
@@ -11326,6 +11395,14 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq) 
	 */

	ufshcd_readl(hba, REG_INTERRUPT_ENABLE);



	mutex_init(&hba->pm_qos.lock);

	INIT_WORK(&hba->pm_qos.get_work, ufshcd_pm_qos_get_worker);

	INIT_WORK(&hba->pm_qos.put_work, ufshcd_pm_qos_put_worker);

	hba->pm_qos.req.type = PM_QOS_REQ_AFFINE_IRQ;

	hba->pm_qos.req.irq = irq;

	pm_qos_add_request(&hba->pm_qos.req, PM_QOS_CPU_DMA_LATENCY,

			   PM_QOS_DEFAULT_VALUE);



	/* IRQ registration */

	err = devm_request_irq(dev, irq, ufshcd_intr, IRQF_SHARED,

				dev_name(dev), hba);
@@ -11427,6 +11504,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq) 
out_remove_scsi_host:

	scsi_remove_host(hba->host);

exit_gating:

	pm_qos_remove_request(&hba->pm_qos.req);

	ufshcd_exit_clk_gating(hba);

	ufshcd_exit_latency_hist(hba);

out_disable:

drivers/scsi/ufs/ufshcd.h

+10 −0
Original line number Diff line number Diff line
@@ -58,6 +58,7 @@ 
#include <linux/regulator/consumer.h>

#include <linux/reset.h>

#include <linux/extcon.h>

#include <linux/pm_qos.h>

#include "unipro.h"



#include <asm/irq.h>
@@ -1086,6 +1087,15 @@ struct ufs_hba { 
	struct keyslot_manager *ksm;

	void *crypto_DO_NOT_USE[8];

#endif /* CONFIG_SCSI_UFS_CRYPTO */



	struct {

		struct pm_qos_request req;

		struct work_struct get_work;

		struct work_struct put_work;

		struct mutex lock;

		atomic_t count;

		bool active;

	} pm_qos;

};



static inline void ufshcd_mark_shutdown_ongoing(struct ufs_hba *hba)