linux-kernel - Re: [PATCH v3 1/4] PCI: pciehp: Add pciehp_set_indicators() to jointly set LED indicators

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Message-ID: <20190821235824.GC28404@skuppusw-desk.amr.corp.intel.com>
Date:   Wed, 21 Aug 2019 16:58:24 -0700
From:   Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Denis Efremov <efremov@...ux.com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Lukas Wunner <lukas@...ner.de>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/4] PCI: pciehp: Add pciehp_set_indicators() to
 jointly set LED indicators

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@...ux.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
> 

-- 
-- 
Sathyanarayanan Kuppuswamy
Linux kernel developer