linux-kernel - Re: [PATCH v2 1/4] PCI: pciehp: Add pciehp_set_indicators() to jointly set LED indicators

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Date:   Mon, 12 Aug 2019 11:25:43 -0700
From:   sathyanarayanan kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Denis Efremov <efremov@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Lukas Wunner <lukas@...ner.de>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/4] PCI: pciehp: Add pciehp_set_indicators() to
 jointly set LED indicators

Hi,

On 8/11/19 12:59 PM, 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.
> enum pciehp_indicator introduced to switch between the indicators statuses.
>
> Signed-off-by: Denis Efremov <efremov@...ux.com>
> ---
>   drivers/pci/hotplug/pciehp.h     | 14 ++++++++++++
>   drivers/pci/hotplug/pciehp_hpc.c | 38 ++++++++++++++++++++++++++++++++
>   include/uapi/linux/pci_regs.h    |  2 ++
>   3 files changed, 54 insertions(+)
>
> diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
> index 8c51a04b8083..17305a6f01f1 100644
> --- a/drivers/pci/hotplug/pciehp.h
> +++ b/drivers/pci/hotplug/pciehp.h
> @@ -150,6 +150,17 @@ struct controller {
>   #define NO_CMD_CMPL(ctrl)	((ctrl)->slot_cap & PCI_EXP_SLTCAP_NCCS)
>   #define PSN(ctrl)		(((ctrl)->slot_cap & PCI_EXP_SLTCAP_PSN) >> 19)
>   
> +enum pciehp_indicator {
> +	ATTN_NONE  = -1,
> +	ATTN_ON    =  1,
> +	ATTN_BLINK =  2,
> +	ATTN_OFF   =  3,
> +	PWR_NONE   = -1,
> +	PWR_ON     =  1,
> +	PWR_BLINK  =  2,
> +	PWR_OFF    =  3,
> +};
> +
>   void pciehp_request(struct controller *ctrl, int action);
>   void pciehp_handle_button_press(struct controller *ctrl);
>   void pciehp_handle_disable_request(struct controller *ctrl);
> @@ -167,6 +178,9 @@ 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,
> +			   enum pciehp_indicator pwr,
> +			   enum pciehp_indicator 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..5a690b1579ec 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -443,6 +443,44 @@ 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,
> +			   enum pciehp_indicator pwr,
> +			   enum pciehp_indicator attn)
> +{
> +	u16 cmd = 0, mask = 0;
> +
> +	if ((!PWR_LED(ctrl)  || pwr  == PWR_NONE) &&
> +	    (!ATTN_LED(ctrl) || attn == ATTN_NONE))
> +		return;
> +
> +	switch (pwr) {
> +	case PWR_ON:
> +	case PWR_BLINK:
> +	case PWR_OFF:
> +		cmd = pwr << PCI_EXP_SLTCTL_PWR_IND_OFFSET;
> +		mask = PCI_EXP_SLTCTL_PIC;
> +		break;
> +	default:
> +		break;
> +	}
Do we need to switch case here ? if (pwr > 0) {} should work right ?
> +
> +	switch (attn) {
> +	case ATTN_ON:
> +	case ATTN_BLINK:
> +	case ATTN_OFF:
> +		cmd |= attn << PCI_EXP_SLTCTL_ATTN_IND_OFFSET;
> +		mask |= PCI_EXP_SLTCTL_AIC;
> +		break;
> +	default:
> +		break;
> +	}
Same here. if (attn > 0) {}
> +
> +	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..18722d1f54a0 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_OFFSET 0x6   /* Attention Indicator Offset */
>   #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_OFFSET 0x8    /* Power Indicator Offset */
>   #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 */

-- 
Sathyanarayanan Kuppuswamy
Linux kernel developer