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Date:   Fri, 13 Oct 2023 15:02:49 -0500
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Ilpo =?utf-8?B?SsOkcnZpbmVu?= <ilpo.jarvinen@linux.intel.com>
Cc:     linux-pci@vger.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: [PATCH 06/10] PCI/DPC: Use FIELD_GET()
Message-ID: <20231013200249.GA1123559@bhelgaas>
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On Wed, Oct 11, 2023 at 02:01:13PM +0300, Ilpo Järvinen wrote:
> On Tue, 10 Oct 2023, Bjorn Helgaas wrote:
> > From: Bjorn Helgaas <bhelgaas@google.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@google.com>
> > ---
> >  drivers/pci/pcie/dpc.c        | 9 +++++----
> >  drivers/pci/quirks.c          | 2 +-
> >  include/uapi/linux/pci_regs.h | 1 +
> >  3 files changed, 7 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> > index 3ceed8e3de41..6e551f34ec63 100644
> > --- a/drivers/pci/pcie/dpc.c
> > +++ b/drivers/pci/pcie/dpc.c
> > @@ -8,6 +8,7 @@
> >  
> >  #define dev_fmt(fmt) "DPC: " fmt
> >  
> > +#include <linux/bitfield.h>
> >  #include <linux/aer.h>
> >  #include <linux/delay.h>
> >  #include <linux/interrupt.h>
> > @@ -202,7 +203,7 @@ static void dpc_process_rp_pio_error(struct pci_dev *pdev)
> >  
> >  	/* Get First Error Pointer */
> >  	pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &dpc_status);
> > -	first_error = (dpc_status & 0x1f00) >> 8;
> > +	first_error = FIELD_GET(PCI_EXP_DPC_STATUS_FIRST_ERR, dpc_status);
> >  
> >  	for (i = 0; i < ARRAY_SIZE(rp_pio_error_string); i++) {
> >  		if ((status & ~mask) & (1 << i))
> > @@ -270,8 +271,8 @@ void dpc_process_error(struct pci_dev *pdev)
> >  	pci_info(pdev, "containment event, status:%#06x source:%#06x\n",
> >  		 status, source);
> >  
> > -	reason = (status & PCI_EXP_DPC_STATUS_TRIGGER_RSN) >> 1;
> > -	ext_reason = (status & PCI_EXP_DPC_STATUS_TRIGGER_RSN_EXT) >> 5;
> > +	reason = FIELD_GET(PCI_EXP_DPC_STATUS_TRIGGER_RSN, status);
> > +	ext_reason = FIELD_GET(PCI_EXP_DPC_STATUS_TRIGGER_RSN_EXT, status);
> >  	pci_warn(pdev, "%s detected\n",
> >  		 (reason == 0) ? "unmasked uncorrectable error" :
> >  		 (reason == 1) ? "ERR_NONFATAL" :
> 
> BTW, it seems we're doing overlapping work here with many of these 
> patches. It takes some time to think these through one by one, I don't 
> just autorun through them with coccinelle so I've not posted my changes
> yet.
>
> I went to a different direction here and named all the reasons too with 
> defines and used & to get the reason in order to be able to compare with 
> the named reasons.
> 
> You also missed convering one 0xfff4 to use define (although I suspect it 
> never was your goal to go beyond FIELD_GET() here).

Pure FIELD_GET() and FIELD_PREP() was my goal.

If you have patches you prefer, I'll drop mine.  I did these about a
year ago and it seemed like the time to do something with them since
you did the PCI_EXP_LNKSTA_NLW ones and to try to prevent overlapping
work.  Since we've started, I'd like to get as much of it done this
cycle as possible.

Bjorn