Re: [PATCH v4 0/4] Simplify PCIe hotplug indicator control

Bjorn Helgaas
2019-09-05T21:01:06Z

On Tue, Sep 03, 2019 at 02:10:17PM +0300, Denis Efremov wrote:
> PCIe defines two optional hotplug indicators: a Power indicator and an
> Attention indicator. Both are controlled by the same register, and each
> can be on, off or blinking. The current interfaces
> (pciehp_green_led_{on,off,blink}() and pciehp_set_attention_status()) are
> non-uniform and require two register writes in many cases where we could
> do one.
>
> This patchset introduces the new function pciehp_set_indicators(). It
> allows one to set two indicators with a single register write. All
> calls to previous interfaces (pciehp_green_led_* and
> pciehp_set_attention_status()) are replaced with a new one. Thus,
> the amount of duplicated code for setting indicators is reduced.
>
> Changes in v4:
> - Changed the inputs validation in pciehp_set_indicators()
> - Moved PCI_EXP_SLTCTL_ATTN_IND_NONE, PCI_EXP_SLTCTL_PWR_IND_NONE
> to drivers/pci/hotplug/pciehp.h and set to -1 for not interfering
> with reserved values in the PCIe Base spec
> - Added set_power_indicator define
>
> Changes in v3:
> - Changed pciehp_set_indicators() to work with existing
> PCI_EXP_SLTCTL_* macros
> - Reworked the inputs validation in pciehp_set_indicators()
> - Removed pciehp_set_attention_status() and pciehp_green_led_*()
> completely
>
> Denis Efremov (4):
> PCI: pciehp: Add pciehp_set_indicators() to jointly set LED indicators
> PCI: pciehp: Switch LED indicators with a single write
> PCI: pciehp: Remove pciehp_set_attention_status()
> PCI: pciehp: Remove pciehp_green_led_{on,off,blink}()
>
> drivers/pci/hotplug/pciehp.h | 12 ++++--
> drivers/pci/hotplug/pciehp_core.c | 7 ++-
> drivers/pci/hotplug/pciehp_ctrl.c | 26 +++++------
> drivers/pci/hotplug/pciehp_hpc.c | 72 +++++++------------------------
> include/uapi/linux/pci_regs.h | 1 +
> 5 files changed, 45 insertions(+), 73 deletions(-)

Thanks, Denis, I applied these to pci/pciehp for v5.4. I think this
is a great improvement.

I tweaked a few things:

- Updated comments to refer to "Power" intead of "green",
"Attention" instead of "amber", and "Indicator" instead of "LED".

- Replaced PCI_EXP_SLTCTL_ATTN_IND_NONE and
PCI_EXP_SLTCTL_PWR_IND_NONE with INDICATOR_NOOP because I didn't
want them to look like definitions from the spec.

- Dropped set_power_indicator(). It does make things locally easier
to read, but I think the overall benefit of having fewer
interfaces outweighs that.

The interdiff from your v4 is below. Let me know if I broke anything.

diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
index dcbf790b7508..654c972b8ea0 100644
--- a/drivers/pci/hotplug/pciehp.h
+++ b/drivers/pci/hotplug/pciehp.h
@@ -110,9 +110,9 @@ struct controller {
*
* @OFF_STATE: slot is powered off, no subordinate devices are enumerated
* @BLINKINGON_STATE: slot will be powered on after the 5 second delay,
- * green led is blinking
+ * Power Indicator is blinking
* @BLINKINGOFF_STATE: slot will be powered off after the 5 second delay,
- * green led is blinking
+ * Power Indicator is blinking
* @POWERON_STATE: slot is currently powering on
* @POWEROFF_STATE: slot is currently powering off
* @ON_STATE: slot is powered on, subordinate devices have been enumerated
@@ -167,9 +167,7 @@ int pciehp_power_on_slot(struct controller *ctrl);
void pciehp_power_off_slot(struct controller *ctrl);
void pciehp_get_power_status(struct controller *ctrl, u8 *status);

-/* Special values for leaving indicators unchanged */
-#define PCI_EXP_SLTCTL_ATTN_IND_NONE -1 /* Attention Indicator noop */
-#define PCI_EXP_SLTCTL_PWR_IND_NONE -1 /* Power Indicator noop */
+#define INDICATOR_NOOP -1 /* Leave indicator unchanged */
void pciehp_set_indicators(struct controller *ctrl, int pwr, int attn);

void pciehp_get_latch_status(struct controller *ctrl, u8 *status);
@@ -187,9 +185,6 @@ int pciehp_get_attention_status(struct hotplug_slot *hotplug_slot, u8 *status);
int pciehp_set_raw_indicator_status(struct hotplug_slot *h_slot, u8 status);
int pciehp_get_raw_indicator_status(struct hotplug_slot *h_slot, u8 *status);

-#define set_power_indicator(ctrl, x) \
- pciehp_set_indicators(ctrl, (x), PCI_EXP_SLTCTL_ATTN_IND_NONE)
-
static inline const char *slot_name(struct controller *ctrl)
{
return hotplug_slot_name(&ctrl->hotplug_slot);
diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index 7a86ea90ed94..b3122c151b80 100644
--- a/drivers/pci/hotplug/pciehp_core.c
+++ b/drivers/pci/hotplug/pciehp_core.c
@@ -95,7 +95,7 @@ static void cleanup_slot(struct controller *ctrl)
}

/*
- * set_attention_status - Turns the Amber LED for a slot on, off or blink
+ * set_attention_status - Turns the Attention Indicator on, off or blinking
*/
static int set_attention_status(struct hotplug_slot *hotplug_slot, u8 status)
{
@@ -108,7 +108,7 @@ static int set_attention_status(struct hotplug_slot *hotplug_slot, u8 status)
status = PCI_EXP_SLTCTL_ATTN_IND_OFF;

pci_config_pm_runtime_get(pdev);
- pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_NONE, status);
+ pciehp_set_indicators(ctrl, INDICATOR_NOOP, status);
pci_config_pm_runtime_put(pdev);
return 0;
}
diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
index d0f55f695770..21af7b16d7a4 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -30,7 +30,10 @@

static void set_slot_off(struct controller *ctrl)
{
- /* turn off slot, turn on Amber LED, turn off Green LED if supported*/
+ /*
+ * Turn off slot, turn on attention indicator, turn off power
+ * indicator
+ */
if (POWER_CTRL(ctrl)) {
pciehp_power_off_slot(ctrl);

@@ -65,7 +68,8 @@ static int board_added(struct controller *ctrl)
return retval;
}

- set_power_indicator(ctrl, PCI_EXP_SLTCTL_PWR_IND_BLINK);
+ pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_BLINK,
+ INDICATOR_NOOP);

/* Check link training status */
retval = pciehp_check_link_status(ctrl);
@@ -100,7 +104,7 @@ static int board_added(struct controller *ctrl)
}

/**
- * remove_board - Turns off slot and LEDs
+ * remove_board - Turn off slot and Power Indicator
* @ctrl: PCIe hotplug controller where board is being removed
* @safe_removal: whether the board is safely removed (versus surprise removed)
*/
@@ -123,8 +127,8 @@ static void remove_board(struct controller *ctrl, bool safe_removal)
&ctrl->pending_events);
}

- /* turn off Green LED */
- set_power_indicator(ctrl, PCI_EXP_SLTCTL_PWR_IND_OFF);
+ pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_OFF,
+ INDICATOR_NOOP);
}

static int pciehp_enable_slot(struct controller *ctrl);
@@ -171,7 +175,7 @@ void pciehp_handle_button_press(struct controller *ctrl)
ctrl_info(ctrl, "Slot(%s) Powering on due to button press\n",
slot_name(ctrl));
}
- /* blink green LED and turn off amber */
+ /* blink power indicator and turn off attention */
pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_BLINK,
PCI_EXP_SLTCTL_ATTN_IND_OFF);
schedule_delayed_work(&ctrl->button_work, 5 * HZ);
@@ -312,7 +316,8 @@ static int pciehp_enable_slot(struct controller *ctrl)
ret = __pciehp_enable_slot(ctrl);
if (ret && ATTN_BUTTN(ctrl))
/* may be blinking */
- set_power_indicator(ctrl, PCI_EXP_SLTCTL_PWR_IND_OFF);
+ pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_OFF,
+ INDICATOR_NOOP);
pm_runtime_put(&ctrl->pcie->port->dev);

mutex_lock(&ctrl->state_lock);
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 9fd8f99132bb..1a522c1c4177 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -418,17 +418,32 @@ int pciehp_set_raw_indicator_status(struct hotplug_slot *hotplug_slot,
return 0;
}

+/**
+ * pciehp_set_indicators() - set attention indicator, power indicator, or both
+ * @ctrl: PCIe hotplug controller
+ * @pwr: one of:
+ * PCI_EXP_SLTCTL_PWR_IND_ON
+ * PCI_EXP_SLTCTL_PWR_IND_BLINK
+ * PCI_EXP_SLTCTL_PWR_IND_OFF
+ * @attn: one of:
+ * PCI_EXP_SLTCTL_ATTN_IND_ON
+ * PCI_EXP_SLTCTL_ATTN_IND_BLINK
+ * PCI_EXP_SLTCTL_ATTN_IND_OFF
+ *
+ * Either @pwr or @attn can also be INDICATOR_NOOP to leave that indicator
+ * unchanged.
+ */
void pciehp_set_indicators(struct controller *ctrl, int pwr, int attn)
{
u16 cmd = 0, mask = 0;

- if (PWR_LED(ctrl) && pwr > 0) {
- cmd |= pwr;
+ if (PWR_LED(ctrl) && pwr != INDICATOR_NOOP) {
+ cmd |= (pwr & PCI_EXP_SLTCTL_PIC);
mask |= PCI_EXP_SLTCTL_PIC;
}

- if (ATTN_LED(ctrl) && attn > 0) {
- cmd |= attn;
+ if (ATTN_LED(ctrl) && attn != INDICATOR_NOOP) {
+ cmd |= (attn & PCI_EXP_SLTCTL_AIC);
mask |= PCI_EXP_SLTCTL_AIC;
}