[v3,1/4] PCI: pciehp: Add pciehp_set_indicators() to jointly set LED indicators
diff mbox series

Message ID 20190819160643.27998-2-efremov@linux.com
State Superseded
Delegated to: Bjorn Helgaas
Headers show
Series
  • Simplify PCIe hotplug indicator control
Related show

Commit Message

Denis Efremov Aug. 19, 2019, 4:06 p.m. UTC
Add pciehp_set_indicators() to set power and attention indicators with a
single register write. Thus, avoiding waiting twice for Command Complete.

Signed-off-by: Denis Efremov <efremov@linux.com>
---
 drivers/pci/hotplug/pciehp.h     |  1 +
 drivers/pci/hotplug/pciehp_hpc.c | 29 +++++++++++++++++++++++++++++
 include/uapi/linux/pci_regs.h    |  2 ++
 3 files changed, 32 insertions(+)

Comments

Denis Efremov Aug. 19, 2019, 4:16 p.m. UTC | #1
Hi,

On 8/19/19 7:06 PM, Denis Efremov wrote:
> +		switch (pwr) {
> +		case PCI_EXP_SLTCTL_PWR_IND_ON:
> +		case PCI_EXP_SLTCTL_PWR_IND_BLINK:
> +		case PCI_EXP_SLTCTL_PWR_IND_OFF:
> +			cmd |= pwr;
> +			mask |= PCI_EXP_SLTCTL_PIC;
> +		}
> +

On 8/12/19 11:25 AM, sathyanarayanan kuppuswamy wrote:
> Do we need to switch case here ? if (pwr > 0) {} should work right ? 

I saved the switch here from v2. I think switch makes the inputs check more
precise and filters-out all non-valid values. Maybe this check is too strict?

We could use mask here ON|OFF|BLINK for the check, but I don't know how hardware
will handle a case, for example, pwr == ON|BLINK.

Thanks,
Denis
Kuppuswamy Sathyanarayanan Aug. 21, 2019, 11:58 p.m. UTC | #2
On Mon, Aug 19, 2019 at 07:06:40PM +0300, Denis Efremov wrote:
> Add pciehp_set_indicators() to set power and attention indicators with a
> single register write. Thus, avoiding waiting twice for Command Complete.
> 
> Signed-off-by: Denis Efremov <efremov@linux.com>
> ---
>  drivers/pci/hotplug/pciehp.h     |  1 +
>  drivers/pci/hotplug/pciehp_hpc.c | 29 +++++++++++++++++++++++++++++
>  include/uapi/linux/pci_regs.h    |  2 ++
>  3 files changed, 32 insertions(+)
> 
> diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
> index 8c51a04b8083..0e272bf3deb4 100644
> --- a/drivers/pci/hotplug/pciehp.h
> +++ b/drivers/pci/hotplug/pciehp.h
> @@ -167,6 +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);
>  
> +void pciehp_set_indicators(struct controller *ctrl, int pwr, int attn);
>  void pciehp_set_attention_status(struct controller *ctrl, u8 status);
>  void pciehp_get_latch_status(struct controller *ctrl, u8 *status);
>  int pciehp_query_power_fault(struct controller *ctrl);
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index bd990e3371e3..5474b9854a7f 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -443,6 +443,35 @@ void pciehp_set_attention_status(struct controller *ctrl, u8 value)
>  		 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, slot_cmd);
>  }
>  
> +void pciehp_set_indicators(struct controller *ctrl, int pwr, int attn)
> +{
> +	u16 cmd = 0, mask = 0;
> +
> +	if (PWR_LED(ctrl))
> +		switch (pwr) {
> +		case PCI_EXP_SLTCTL_PWR_IND_ON:
> +		case PCI_EXP_SLTCTL_PWR_IND_BLINK:
> +		case PCI_EXP_SLTCTL_PWR_IND_OFF:
> +			cmd |= pwr;
> +			mask |= PCI_EXP_SLTCTL_PIC;
> +		}
> +
> +	if (ATTN_LED(ctrl))
> +		switch (attn) {
> +		case PCI_EXP_SLTCTL_ATTN_IND_ON:
> +		case PCI_EXP_SLTCTL_ATTN_IND_BLINK:
> +		case PCI_EXP_SLTCTL_ATTN_IND_OFF:
> +			cmd |= attn;
> +			mask |= PCI_EXP_SLTCTL_AIC;
> +		}
> +
> +	if (cmd) {
> +		pcie_write_cmd_nowait(ctrl, cmd, mask);
> +		ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,
> +			 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, cmd);
> +	}
> +}
> +
>  void pciehp_green_led_on(struct controller *ctrl)
>  {
>  	if (!PWR_LED(ctrl))
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index f28e562d7ca8..291788b58f3a 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -591,10 +591,12 @@
>  #define  PCI_EXP_SLTCTL_CCIE	0x0010	/* Command Completed Interrupt Enable */
>  #define  PCI_EXP_SLTCTL_HPIE	0x0020	/* Hot-Plug Interrupt Enable */
>  #define  PCI_EXP_SLTCTL_AIC	0x00c0	/* Attention Indicator Control */
> +#define  PCI_EXP_SLTCTL_ATTN_IND_NONE  0x0    /* Attention Indicator noop */
>  #define  PCI_EXP_SLTCTL_ATTN_IND_ON    0x0040 /* Attention Indicator on */
>  #define  PCI_EXP_SLTCTL_ATTN_IND_BLINK 0x0080 /* Attention Indicator blinking */
>  #define  PCI_EXP_SLTCTL_ATTN_IND_OFF   0x00c0 /* Attention Indicator off */
>  #define  PCI_EXP_SLTCTL_PIC	0x0300	/* Power Indicator Control */
> +#define  PCI_EXP_SLTCTL_PWR_IND_NONE   0x0    /* Power Indicator noop */
Nitpick: Since the current patch does not use it, May be you can create a
new patch for these #defines ? or you could add some info about its
usage in comment section.
>  #define  PCI_EXP_SLTCTL_PWR_IND_ON     0x0100 /* Power Indicator on */
>  #define  PCI_EXP_SLTCTL_PWR_IND_BLINK  0x0200 /* Power Indicator blinking */
>  #define  PCI_EXP_SLTCTL_PWR_IND_OFF    0x0300 /* Power Indicator off */
> -- 
> 2.21.0
>
Oliver O'Halloran Aug. 27, 2019, 11:24 p.m. UTC | #3
On Tue, Aug 20, 2019 at 2:17 AM Denis Efremov <efremov@linux.com> wrote:
>
> Hi,
>
> On 8/19/19 7:06 PM, Denis Efremov wrote:
> On 8/12/19 11:25 AM, sathyanarayanan kuppuswamy wrote:
> > Do we need to switch case here ? if (pwr > 0) {} should work right ?
>
> I saved the switch here from v2. I think switch makes the inputs check more
> precise and filters-out all non-valid values. Maybe this check is too strict?

Sounds like you're overthinking it tbh. If want to catch programming
errors then a WARN_ON_ONCE() in the default case would be better than
silently ignoring invalid values, but it's pretty hard to care.

> We could use mask here ON|OFF|BLINK for the check, but I don't know how hardware
> will handle a case, for example, pwr == ON|BLINK.

ON|BLINK is the same as OFF
Oliver O'Halloran Aug. 27, 2019, 11:41 p.m. UTC | #4
On Tue, Aug 20, 2019 at 2:07 AM Denis Efremov <efremov@linux.com> wrote:
>
> Add pciehp_set_indicators() to set power and attention indicators with a
> single register write. Thus, avoiding waiting twice for Command Complete.
>
> Signed-off-by: Denis Efremov <efremov@linux.com>
> ---
>  drivers/pci/hotplug/pciehp.h     |  1 +
>  drivers/pci/hotplug/pciehp_hpc.c | 29 +++++++++++++++++++++++++++++
>  include/uapi/linux/pci_regs.h    |  2 ++
>  3 files changed, 32 insertions(+)
>
> diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
> index 8c51a04b8083..0e272bf3deb4 100644
> --- a/drivers/pci/hotplug/pciehp.h
> +++ b/drivers/pci/hotplug/pciehp.h
> @@ -167,6 +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);
>
> +void pciehp_set_indicators(struct controller *ctrl, int pwr, int attn);
>  void pciehp_set_attention_status(struct controller *ctrl, u8 status);
>  void pciehp_get_latch_status(struct controller *ctrl, u8 *status);
>  int pciehp_query_power_fault(struct controller *ctrl);
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index bd990e3371e3..5474b9854a7f 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -443,6 +443,35 @@ void pciehp_set_attention_status(struct controller *ctrl, u8 value)
>                  pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, slot_cmd);
>  }
>
> +void pciehp_set_indicators(struct controller *ctrl, int pwr, int attn)
> +{
> +       u16 cmd = 0, mask = 0;
> +
> +       if (PWR_LED(ctrl))
> +               switch (pwr) {
> +               case PCI_EXP_SLTCTL_PWR_IND_ON:
> +               case PCI_EXP_SLTCTL_PWR_IND_BLINK:
> +               case PCI_EXP_SLTCTL_PWR_IND_OFF:

Do you need an explicit /* fallthrough */ comment? I thought the
fallthrough warning was enabled by default now.

> +                       cmd |= pwr;
> +                       mask |= PCI_EXP_SLTCTL_PIC;
> +               }
> +
> +       if (ATTN_LED(ctrl))
> +               switch (attn) {
> +               case PCI_EXP_SLTCTL_ATTN_IND_ON:
> +               case PCI_EXP_SLTCTL_ATTN_IND_BLINK:
> +               case PCI_EXP_SLTCTL_ATTN_IND_OFF:
> +                       cmd |= attn;
> +                       mask |= PCI_EXP_SLTCTL_AIC;
> +               }
> +
> +       if (cmd) {
> +               pcie_write_cmd_nowait(ctrl, cmd, mask);
> +               ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,
> +                        pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, cmd);
> +       }
> +}
> +
>  void pciehp_green_led_on(struct controller *ctrl)
>  {
>         if (!PWR_LED(ctrl))
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index f28e562d7ca8..291788b58f3a 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -591,10 +591,12 @@
>  #define  PCI_EXP_SLTCTL_CCIE   0x0010  /* Command Completed Interrupt Enable */
>  #define  PCI_EXP_SLTCTL_HPIE   0x0020  /* Hot-Plug Interrupt Enable */
>  #define  PCI_EXP_SLTCTL_AIC    0x00c0  /* Attention Indicator Control */

> +#define  PCI_EXP_SLTCTL_ATTN_IND_NONE  0x0    /* Attention Indicator noop */
>  #define  PCI_EXP_SLTCTL_ATTN_IND_ON    0x0040 /* Attention Indicator on */
>  #define  PCI_EXP_SLTCTL_ATTN_IND_BLINK 0x0080 /* Attention Indicator blinking */
>  #define  PCI_EXP_SLTCTL_ATTN_IND_OFF   0x00c0 /* Attention Indicator off */
>  #define  PCI_EXP_SLTCTL_PIC    0x0300  /* Power Indicator Control */
> +#define  PCI_EXP_SLTCTL_PWR_IND_NONE   0x0    /* Power Indicator noop */

I don't think pci_regs.h is the right place for this. The contents of
pci_regs.h is essentially a transcription of bit definitions from the
various PCI standards documents. The PCIe Base spec says the the 0b00
combination for the two-bit Power and Attn indicator fields is
reserved and there's nothing suggesting that writing a zero to those
fields should preserve the current value. Basicly, we now have a
implementation quirk of pcie_set_indicators() masquerading as part of
the standard.

>  #define  PCI_EXP_SLTCTL_PWR_IND_ON     0x0100 /* Power Indicator on */
>  #define  PCI_EXP_SLTCTL_PWR_IND_BLINK  0x0200 /* Power Indicator blinking */
>  #define  PCI_EXP_SLTCTL_PWR_IND_OFF    0x0300 /* Power Indicator off */
> --
> 2.21.0
>

Patch
diff mbox series

diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
index 8c51a04b8083..0e272bf3deb4 100644
--- a/drivers/pci/hotplug/pciehp.h
+++ b/drivers/pci/hotplug/pciehp.h
@@ -167,6 +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);
 
+void pciehp_set_indicators(struct controller *ctrl, int pwr, int attn);
 void pciehp_set_attention_status(struct controller *ctrl, u8 status);
 void pciehp_get_latch_status(struct controller *ctrl, u8 *status);
 int pciehp_query_power_fault(struct controller *ctrl);
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index bd990e3371e3..5474b9854a7f 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -443,6 +443,35 @@  void pciehp_set_attention_status(struct controller *ctrl, u8 value)
 		 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, slot_cmd);
 }
 
+void pciehp_set_indicators(struct controller *ctrl, int pwr, int attn)
+{
+	u16 cmd = 0, mask = 0;
+
+	if (PWR_LED(ctrl))
+		switch (pwr) {
+		case PCI_EXP_SLTCTL_PWR_IND_ON:
+		case PCI_EXP_SLTCTL_PWR_IND_BLINK:
+		case PCI_EXP_SLTCTL_PWR_IND_OFF:
+			cmd |= pwr;
+			mask |= PCI_EXP_SLTCTL_PIC;
+		}
+
+	if (ATTN_LED(ctrl))
+		switch (attn) {
+		case PCI_EXP_SLTCTL_ATTN_IND_ON:
+		case PCI_EXP_SLTCTL_ATTN_IND_BLINK:
+		case PCI_EXP_SLTCTL_ATTN_IND_OFF:
+			cmd |= attn;
+			mask |= PCI_EXP_SLTCTL_AIC;
+		}
+
+	if (cmd) {
+		pcie_write_cmd_nowait(ctrl, cmd, mask);
+		ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,
+			 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, cmd);
+	}
+}
+
 void pciehp_green_led_on(struct controller *ctrl)
 {
 	if (!PWR_LED(ctrl))
diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index f28e562d7ca8..291788b58f3a 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -591,10 +591,12 @@ 
 #define  PCI_EXP_SLTCTL_CCIE	0x0010	/* Command Completed Interrupt Enable */
 #define  PCI_EXP_SLTCTL_HPIE	0x0020	/* Hot-Plug Interrupt Enable */
 #define  PCI_EXP_SLTCTL_AIC	0x00c0	/* Attention Indicator Control */
+#define  PCI_EXP_SLTCTL_ATTN_IND_NONE  0x0    /* Attention Indicator noop */
 #define  PCI_EXP_SLTCTL_ATTN_IND_ON    0x0040 /* Attention Indicator on */
 #define  PCI_EXP_SLTCTL_ATTN_IND_BLINK 0x0080 /* Attention Indicator blinking */
 #define  PCI_EXP_SLTCTL_ATTN_IND_OFF   0x00c0 /* Attention Indicator off */
 #define  PCI_EXP_SLTCTL_PIC	0x0300	/* Power Indicator Control */
+#define  PCI_EXP_SLTCTL_PWR_IND_NONE   0x0    /* Power Indicator noop */
 #define  PCI_EXP_SLTCTL_PWR_IND_ON     0x0100 /* Power Indicator on */
 #define  PCI_EXP_SLTCTL_PWR_IND_BLINK  0x0200 /* Power Indicator blinking */
 #define  PCI_EXP_SLTCTL_PWR_IND_OFF    0x0300 /* Power Indicator off */