linux-kernel - Re: [PATCH 08/10] PCI/PTM: Use FIELD

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Date:   Wed, 11 Oct 2023 14:15:36 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
cc:     linux-pci@...r.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH 08/10] PCI/PTM: Use FIELD_GET()

On Tue, 10 Oct 2023, Bjorn Helgaas wrote:

> From: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> Use FIELD_GET() to remove dependences on the field position, i.e., the
> shift value.  No functional change intended.
> 
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>

You seem to be using FIELD_PREP() too below.


> ---
>  drivers/pci/pcie/ptm.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
> index b4e5f553467c..7cfb6c0d5dcb 100644
> --- a/drivers/pci/pcie/ptm.c
> +++ b/drivers/pci/pcie/ptm.c
> @@ -4,6 +4,7 @@
>   * Copyright (c) 2016, Intel Corporation.
>   */
>  
> +#include <linux/bitfield.h>
>  #include <linux/module.h>
>  #include <linux/init.h>
>  #include <linux/pci.h>
> @@ -53,7 +54,7 @@ void pci_ptm_init(struct pci_dev *dev)
>  	pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_PTM, sizeof(u32));
>  
>  	pci_read_config_dword(dev, ptm + PCI_PTM_CAP, &cap);
> -	dev->ptm_granularity = (cap & PCI_PTM_GRANULARITY_MASK) >> 8;
> +	dev->ptm_granularity = FIELD_GET(PCI_PTM_GRANULARITY_MASK, cap);
>  
>  	/*
>  	 * Per the spec recommendation (PCIe r6.0, sec 7.9.15.3), select the
> @@ -146,7 +147,7 @@ static int __pci_enable_ptm(struct pci_dev *dev)
>  
>  	ctrl |= PCI_PTM_CTRL_ENABLE;
>  	ctrl &= ~PCI_PTM_GRANULARITY_MASK;
> -	ctrl |= dev->ptm_granularity << 8;
> +	ctrl |= FIELD_PREP(PCI_PTM_GRANULARITY_MASK, dev->ptm_granularity);
>  	if (dev->ptm_root)
>  		ctrl |= PCI_PTM_CTRL_ROOT;
>  
> 


-- 
 i.