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scsi: ufs: core: Hold a clock reference across the probe

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Clock gating becomes possible as soon as ufshcd_init_clk_gating() has run,
and from that point on the probe keeps accessing host registers without
ever taking a clock reference. This has been safe only because of the state
check in __ufshcd_release(): gate_work is not queued unless
hba->ufshcd_state is UFSHCD_STATE_OPERATIONAL, and the promotion to that
state used to happen after the last register access of the probe, at the
end of ufshcd_probe_hba().

That is fragile: it only works while the promotion happens after the
register accesses. Commit a390e6677f ("scsi: ufs: core: Expand the
ufshcd_device_init(hba, true) call") changed that ordering by moving the
promotion into ufshcd_init(), which schedules ufshcd_async_scan()
afterwards. ufshcd_probe_hba() therefore now runs with the state already
promoted, and it accesses host registers without holding a clock reference:

 - On hosts with UFSHCD_QUIRK_REINIT_AFTER_MAX_GEAR_SWITCH it calls
   ufshcd_hba_stop() and ufshcd_hba_enable() before ufshcd_device_init()
   sets the state back to UFSHCD_STATE_RESET, and both read
   REG_CONTROLLER_ENABLE, so gated clocks stall there instead of just
   losing a write.

 - It ends with an ufshcd_configure_auto_hibern8() write, which its other
   callers do take a clock reference for.

Take a clock reference as soon as clock gating has been initialised and
keep it until the probe is over. It then does not matter who drops a clock
reference while the probe is running, and the register accesses of the
probe no longer depend on hba->ufshcd_state. The reference is dropped by
ufshcd_async_scan() once the scan has finished, or by the new out_release
label if the probe fails after it was taken.

Fixes: a390e6677f ("scsi: ufs: core: Expand the ufshcd_device_init(hba, true) call")
Signed-off-by: Naomi Chu <naomi.chu@mediatek.com>
Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Link: https://patch.msgid.link/20260909091045.1134956-1-naomi.chu@mediatek.com
Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>
This commit is contained in:
Naomi Chu 2026-09-09 17:10:45 +08:00 committed by Martin K. Petersen (Oracle)
parent 42d1221d32
commit 02a3178319
1 changed files with 14 additions and 8 deletions
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22
drivers/ufs/core/ufshcd.c
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@ -9556,6 +9556,7 @@ static void ufshcd_async_scan(void *data, async_cookie_t cookie)
ret = ufshcd_add_lus(hba);
out:
ufshcd_release(hba);
pm_runtime_put_sync(hba->dev);
if (ret)
@ -11278,6 +11279,9 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
ufshcd_init_clk_gating(hba);
/* Released by ufshcd_async_scan(), or by out_release on failure. */
ufshcd_hold(hba);
ufshcd_init_clk_scaling(hba);
/*
@ -11298,7 +11302,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
err = devm_request_irq(dev, irq, ufshcd_intr, IRQF_SHARED, UFSHCD, hba);
if (err) {
dev_err(hba->dev, "request irq failed\n");
goto out_disable;
goto out_release;
} else {
hba->is_irq_enabled = true;
}
@ -11314,7 +11318,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
dev_err(hba->dev, "Host controller enable failed\n");
ufshcd_print_evt_hist(hba);
ufshcd_print_host_state(hba);
goto out_disable;
goto out_release;
}
INIT_DELAYED_WORK(&hba->rpm_dev_flush_recheck_work, ufshcd_rpm_dev_flush_recheck_work);
@ -11328,7 +11332,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
err = ufshcd_add_scsi_host(hba);
if (err)
goto out_disable;
goto out_release;
/* Hold auto suspend until async scan completes */
pm_runtime_get_sync(dev);
@ -11348,7 +11352,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
err = ufshcd_link_startup(hba);
if (err)
goto out_disable;
goto out_release;
if (hba->mcq_enabled)
ufshcd_config_mcq(hba);
@ -11365,23 +11369,23 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
/* Verify device initialization by sending NOP OUT UPIU */
err = ufshcd_verify_dev_init(hba);
if (err)
goto out_disable;
goto out_release;
/* Initiate UFS initialization, and waiting until completion */
err = ufshcd_complete_dev_init(hba);
if (err)
goto out_disable;
goto out_release;
err = ufshcd_device_params_init(hba);
if (err)
goto out_disable;
goto out_release;
err = ufshcd_post_device_init(hba);
initialized:
ufshcd_process_probe_result(hba, probe_start, err);
if (err)
goto out_disable;
goto out_release;
ufs_sysfs_add_nodes(hba->dev);
hba->dme_qos_sysfs_handle = sysfs_get_dirent(hba->dev->kobj.sd,
@ -11392,6 +11396,8 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
ufshcd_pm_qos_init(hba);
return 0;
out_release:
ufshcd_release(hba);
out_disable:
hba->is_irq_enabled = false;
ufshcd_hba_exit(hba);