On 9/9/2022 2:34 PM, Dmitry Baryshkov wrote:

On Fri, 9 Sept 2022 at 11:45, Krishna chaitanya chundru
[off-list ref] wrote:

quoted

Introducing phy power down/up callbacks for allowing to park the
link-state in L1ss without holding any PCIe resources during
system suspend.

Signed-off-by: Krishna chaitanya chundru <redacted>
---
  drivers/phy/phy-core.c  | 30 ++++++++++++++++++++++++++++++
  include/linux/phy/phy.h | 20 ++++++++++++++++++++
  2 files changed, 50 insertions(+)

diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
index d93ddf1..1b0b757 100644
--- a/drivers/phy/phy-core.c
+++ b/drivers/phy/phy-core.c

@@ -441,6 +441,36 @@ int phy_set_speed(struct phy *phy, int speed)
  }
  EXPORT_SYMBOL_GPL(phy_set_speed);

+int phy_power_down(struct phy *phy)
+{
+       int ret;
+
+       if (!phy || !phy->ops->power_down)
+               return 0;
+
+       mutex_lock(&phy->mutex);
+       ret = phy->ops->power_down(phy);
+       mutex_unlock(&phy->mutex);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(phy_power_down);
+
+int phy_power_up(struct phy *phy)
+{
+       int ret;
+
+       if (!phy || !phy->ops->power_up)
+               return 0;
+
+       mutex_lock(&phy->mutex);
+       ret = phy->ops->power_up(phy);
+       mutex_unlock(&phy->mutex);
+
+       return ret;
+}

As it can be seen from the phy_power_off(), the PHY can be a shared
resource, with the power_count counting the number of users that
requested the PHY to be powered up. By introducing suc calls you break
directly into this by allowing a single user to power down the PHY, no
matter how many other users have requested the PHY to stay alive.

can we use same power_count in this function also here and restrict the 
single user to

power down the PHY same like phy_power_off?.

quoted

+EXPORT_SYMBOL_GPL(phy_power_up);
+
  int phy_reset(struct phy *phy)
  {
         int ret;

diff --git a/include/linux/phy/phy.h b/include/linux/phy/phy.h
index b141375..3a45f4d 100644
--- a/include/linux/phy/phy.h
+++ b/include/linux/phy/phy.h

@@ -76,6 +76,8 @@ union phy_configure_opts {
   * @set_mode: set the mode of the phy
   * @set_media: set the media type of the phy (optional)
   * @set_speed: set the speed of the phy (optional)
+ * @power_down: parking the phy in power down state
+ * @power_up: pulling back the phy from power down
   * @reset: resetting the phy
   * @calibrate: calibrate the phy
   * @release: ops to be performed while the consumer relinquishes the PHY

@@ -89,6 +91,8 @@ struct phy_ops {
         int     (*set_mode)(struct phy *phy, enum phy_mode mode, int submode);
         int     (*set_media)(struct phy *phy, enum phy_media media);
         int     (*set_speed)(struct phy *phy, int speed);
+       int     (*power_down)(struct phy *phy);
+       int     (*power_up)(struct phy *phy);

         /**
          * @configure:

@@ -226,6 +230,8 @@ int phy_init(struct phy *phy);
  int phy_exit(struct phy *phy);
  int phy_power_on(struct phy *phy);
  int phy_power_off(struct phy *phy);
+int phy_power_down(struct phy *phy);
+int phy_power_up(struct phy *phy);
  int phy_set_mode_ext(struct phy *phy, enum phy_mode mode, int submode);
  #define phy_set_mode(phy, mode) \
         phy_set_mode_ext(phy, mode, 0)

@@ -349,6 +355,20 @@ static inline int phy_power_off(struct phy *phy)
         return -ENOSYS;
  }

+static inline int phy_power_down(struct phy *phy)
+{
+       if (!phy)
+               return 0;
+       return -ENOSYS;
+}
+
+static inline int phy_power_up(struct phy *phy)
+{
+       if (!phy)
+               return 0;
+       return -ENOSYS;
+}
+
  static inline int phy_set_mode_ext(struct phy *phy, enum phy_mode mode,
                                    int submode)
  {
--

2.7.4

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