[PATCH 1/3] phy: qcom-qmp-ufs: support dynamic gear changing

[Vladimir Oltean]

Currently, phy_set_mode_ext() on the QMP UFS PHY expects the PHY to be
powered down, and it makes no change to the hardware state, instead
phy_power_on() followed by phy_calibrate() must be run afterwards.

"Order of API calls" from Documentation/driver-api/phy/phy.rst has a
roundabout and not really clear way of saying that both calling
sequences should be supported. This was further discussed here,
documentation is pending an update:
https://lore.kernel.org/linux-phy/E1vo0mF-00000007kbg-1OeA@xxxxxxxxxxxxxxxxxxxxxx/

By absorbing the phy_power_off() -> ... -> phy_power_on() ->
phy_configure() surrounding sequence into phy_set_mode_ext(), consumer
drivers can be greatly simplified, and we also have a proper
self-standing phy_set_mode_ext() implementation which does not rely on
other calls to do its job.

Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
---
 drivers/phy/qualcomm/phy-qcom-qmp-ufs.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c b/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c
index df138a5442eb..e75b059bf246 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c
@@ -2004,15 +2004,24 @@ static int qmp_ufs_set_mode(struct phy *phy, enum phy_mode mode, int submode)
 {
 	struct qmp_ufs *qmp = phy_get_drvdata(phy);
 	const struct qmp_phy_cfg *cfg = qmp->cfg;
+	bool powered_on = phy->power_count;
 
 	if (submode > cfg->max_supported_gear || submode == 0) {
 		dev_err(qmp->dev, "Invalid PHY submode %d\n", submode);
 		return -EINVAL;
 	}
 
+	if (powered_on)
+		qmp_ufs_power_off(phy);
+
 	qmp->mode = mode;
 	qmp->submode = submode;
 
+	if (powered_on) {
+		qmp_ufs_power_on(phy);
+		return qmp_ufs_phy_calibrate(phy);
+	}
+
 	return 0;
 }
 
-- 
2.34.1


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