linux-kernel - Re: [PATCH 5/7] rtlwifi: rtl8821ae: Use pci_find

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Message-ID: <20231117224633.GA96129@bhelgaas>
Date:   Fri, 17 Nov 2023 16:46:33 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc:     "John W. Linville" <linville@...driver.com>,
        Kalle Valo <kvalo@...nel.org>,
        Larry Finger <Larry.Finger@...inger.net>,
        linux-wireless@...r.kernel.org, Ping-Ke Shih <pkshih@...ltek.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/7] rtlwifi: rtl8821ae: Use pci_find_capability()

On Fri, Nov 17, 2023 at 11:44:23AM +0200, Ilpo Järvinen wrote:
> Instead of open coding the capability structure search, find the PM
> Capability using pci_find_capability().
>
> While at it, rename the generic 'cap_pointer' to 'pm_cap' which makes
> the intent of the code more obvious.
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> ---
>  .../wireless/realtek/rtlwifi/rtl8821ae/hw.c   | 49 +++----------------
>  1 file changed, 8 insertions(+), 41 deletions(-)
> 
> diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/hw.c b/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/hw.c
> index 53cfeed0b030..7877509c34c7 100644
> --- a/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/hw.c
> +++ b/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/hw.c
> @@ -2270,42 +2270,11 @@ static void _rtl8821ae_clear_pci_pme_status(struct ieee80211_hw *hw)
>  {
>  	struct rtl_priv *rtlpriv = rtl_priv(hw);
>  	struct rtl_pci *rtlpci = rtl_pcidev(rtl_pcipriv(hw));
> -	u16 cap_hdr;
> -	u8 cap_pointer;
> -	u8 cap_id = 0xff;
>  	u8 pmcs_reg;
> -	u8 cnt = 0;
> +	u8 pm_cap;
>  
> -	/* Get the Capability pointer first,
> -	 * the Capability Pointer is located at
> -	 * offset 0x34 from the Function Header */
> -
> -	pci_read_config_byte(rtlpci->pdev, 0x34, &cap_pointer);
> -	rtl_dbg(rtlpriv, COMP_INIT, DBG_LOUD,
> -		"PCI configuration 0x34 = 0x%2x\n", cap_pointer);
> -
> -	do {
> -		pci_read_config_word(rtlpci->pdev, cap_pointer, &cap_hdr);
> -		cap_id = cap_hdr & 0xFF;
> -
> -		rtl_dbg(rtlpriv, COMP_INIT, DBG_LOUD,
> -			"in pci configuration, cap_pointer%x = %x\n",
> -			cap_pointer, cap_id);
> -
> -		if (cap_id == 0x01) {
> -			break;
> -		} else {
> -			/* point to next Capability */
> -			cap_pointer = (cap_hdr >> 8) & 0xFF;
> -			/* 0: end of pci capability, 0xff: invalid value */
> -			if (cap_pointer == 0x00 || cap_pointer == 0xff) {
> -				cap_id = 0xff;
> -				break;
> -			}
> -		}
> -	} while (cnt++ < 200);
> -
> -	if (cap_id != 0x01) {
> +	pm_cap = pci_find_capability(rtlpci->pdev, PCI_CAP_ID_PM);

Hahaha, good work.

> +	if (!pm_cap) {
>  		rtl_dbg(rtlpriv, COMP_INIT, DBG_WARNING,
>  			"Cannot find PME Capability\n");
>  		return;
> @@ -2314,22 +2283,20 @@ static void _rtl8821ae_clear_pci_pme_status(struct ieee80211_hw *hw)
>  	/* Get the PM CSR (Control/Status Register),
>  	 * The PME_Status is located at PM Capatibility offset 5, bit 7

Same comment typo and PCI_PM_CTRL, PCI_PM_CTRL_PME_STATUS comments as
before.

> -	pci_read_config_byte(rtlpci->pdev, cap_pointer + 5, &pmcs_reg);
> +	pci_read_config_byte(rtlpci->pdev, pm_cap + 5, &pmcs_reg);
>  
>  	if (pmcs_reg & BIT(7)) {
>  		/* Clear PME_Status with write */
> -		pci_write_config_byte(rtlpci->pdev, cap_pointer + 5,
> -				      pmcs_reg);
> +		pci_write_config_byte(rtlpci->pdev, pm_cap + 5, pmcs_reg);
>  		/* Read it back to check */
> -		pci_read_config_byte(rtlpci->pdev, cap_pointer + 5,
> -				     &pmcs_reg);
> +		pci_read_config_byte(rtlpci->pdev, pm_cap + 5, &pmcs_reg);
>  		rtl_dbg(rtlpriv, COMP_INIT, DBG_DMESG,
>  			"Clear PME status 0x%2x to 0x%2x\n",
> -			cap_pointer + 5, pmcs_reg);
> +			pm_cap + 5, pmcs_reg);
>  	} else {
>  		rtl_dbg(rtlpriv, COMP_INIT, DBG_DMESG,
>  			"PME status(0x%2x) = 0x%2x\n",
> -			cap_pointer + 5, pmcs_reg);
> +			pm_cap + 5, pmcs_reg);
>  	}
>  }
>  
> -- 
> 2.30.2
>