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

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Message-ID: <20190905220327.poa6sknhei6tj47v@wunner.de>
Date:   Fri, 6 Sep 2019 00:03:27 +0200
From:   Lukas Wunner <lukas@...ner.de>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Denis Efremov <efremov@...ux.com>, linux-pci@...r.kernel.org,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Oliver O'Halloran <oohall@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 0/4] Simplify PCIe hotplug indicator control

On Thu, Sep 05, 2019 at 04:01:02PM -0500, Bjorn Helgaas wrote:
>  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;
>  	}

There's a subtle issue here:  A value of "0" is "reserved" per PCIe r4.0,
sec 7.8.10.  Denis filtered that out, with your change it's an accepted
value.  I don't think the function ever gets called with a value of "0",
so it's not a big deal.  And maybe we don't even want to filter that
value out.  Just noting anyway.

Thanks,

Lukas