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From: "Marek Behún" <kabel@kernel.org>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	linux-pci@vger.kernel.org, pali@kernel.org
Subject: Re: [PATCH 09/13] PCI: aardvark: Implement re-issuing config requests on CRS response
Date: Mon, 4 Oct 2021 12:19:38 +0200	[thread overview]
Message-ID: <20211004121938.546d8f73@thinkpad> (raw)
In-Reply-To: <20211004085335.GC22336@lpieralisi>

On Mon, 4 Oct 2021 09:53:35 +0100
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> wrote:

> On Mon, Oct 04, 2021 at 09:21:48AM +0200, Marek Behún wrote:
> > On Sat, 2 Oct 2021 11:35:19 -0500
> > Bjorn Helgaas <helgaas@kernel.org> wrote:
> >   
> > > On Fri, Oct 01, 2021 at 09:58:52PM +0200, Marek Behún wrote:  
> > > > From: Pali Rohár <pali@kernel.org>
> > > > 
> > > > Commit 43f5c77bcbd2 ("PCI: aardvark: Fix reporting CRS value") fixed
> > > > handling of CRS response and when CRSSVE flag was not enabled it marked CRS
> > > > response as failed transaction (due to simplicity).
> > > > 
> > > > But pci-aardvark.c driver is already waiting up to the PIO_RETRY_CNT count
> > > > for PIO config response and so we can with a small change implement
> > > > re-issuing of config requests as described in PCIe base specification.
> > > > 
> > > > This change implements re-issuing of config requests when response is CRS.
> > > > Set upper bound of wait cycles to around PIO_RETRY_CNT, afterwards the
> > > > transaction is marked as failed and an all-ones value is returned as
> > > > before.    
> > > 
> > > Does this fix a problem?  
> > 
> > Hello Bjorn,
> > 
> > Pali has suspisions that certain Marvell WiFi cards may need this [1]
> > to work, but we do not have them so we cannot test this.
> > 
> > I guess you think this should be considered a new feature instead of a
> > fix, so that the Fixes tag should be removed, yes? Pali was of the
> > opinion that this patch "fixes" the driver to conform more to the PCIe
> > specification, that is why we added the Fixes tag.
> > 
> > Anyway if you think this should be considered a new feature, this patch
> > can be skipped. The following patches apply even without it.  
> 
> I do not think we should apply to the mainline a fix that can't be
> tested sorry, I will skip this patch.

Lorenzo,

my explanation was incorrect.

The functionality added by this patch _is_ tested and correctly does a
retry: it was done by simulating a CRS reply.

We just don't know whether there are real cards used by users that
need this functionality (the mentioned Marvell card may be such a card).

Marek

  reply	other threads:[~2021-10-04 10:19 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-01 19:58 [PATCH 00/13] PCI: aardvark controller fixes Marek Behún
2021-10-01 19:58 ` [PATCH 01/13] PCI: Add PCI_EXP_DEVCTL_PAYLOAD_* macros Marek Behún
2021-10-02 16:05   ` Bjorn Helgaas
2021-10-04  8:43   ` Lorenzo Pieralisi
2021-10-04  9:32     ` Marek Behún
2021-10-04  9:35       ` Lorenzo Pieralisi
2021-10-01 19:58 ` [PATCH 02/13] PCI: aardvark: Fix PCIe Max Payload Size setting Marek Behún
2021-10-03 17:44   ` Marek Behún
2021-10-01 19:58 ` [PATCH 03/13] PCI: aardvark: Don't spam about PIO Response Status Marek Behún
2021-10-01 19:58 ` [PATCH 04/13] PCI: aardvark: Fix preserving PCI_EXP_RTCTL_CRSSVE flag on emulated bridge Marek Behún
2021-10-01 19:58 ` [PATCH 05/13] PCI: aardvark: Fix configuring Reference clock Marek Behún
2021-10-01 19:58 ` [PATCH 06/13] PCI: aardvark: Do not clear status bits of masked interrupts Marek Behún
2021-10-04 14:06   ` Lorenzo Pieralisi
2021-10-04 15:18     ` Marek Behún
2021-10-04 15:31     ` Marc Zyngier
2021-10-05 12:13       ` Marek Behún
2021-10-05 12:42         ` Marc Zyngier
2021-10-05 13:15           ` Pali Rohár
2021-10-05 15:42             ` Marc Zyngier
2021-10-05 18:48               ` Pali Rohár
2021-10-05 16:04             ` Lorenzo Pieralisi
2021-10-01 19:58 ` [PATCH 07/13] PCI: aardvark: Do not unmask unused interrupts Marek Behún
2021-10-01 19:58 ` [PATCH 08/13] PCI: aardvark: Deduplicate code in advk_pcie_rd_conf() Marek Behún
2021-10-01 19:58 ` [PATCH 09/13] PCI: aardvark: Implement re-issuing config requests on CRS response Marek Behún
2021-10-02 16:35   ` Bjorn Helgaas
2021-10-04  7:21     ` Marek Behún
2021-10-04  8:53       ` Lorenzo Pieralisi
2021-10-04 10:19         ` Marek Behún [this message]
2021-10-05 19:28           ` Bjorn Helgaas
2021-10-05 22:45             ` Marek Behún
2021-10-11 18:15               ` Usage of PCBIOS_* macros (Was: Re: [PATCH 09/13] PCI: aardvark: Implement re-issuing config requests on CRS response) Pali Rohár
2021-10-11 20:58                 ` Bjorn Helgaas
2021-10-06 16:29             ` [PATCH 09/13] PCI: aardvark: Implement re-issuing config requests on CRS response Lorenzo Pieralisi
2021-10-06 20:13               ` Bjorn Helgaas
2021-10-07 11:51                 ` Lorenzo Pieralisi
2021-10-07 12:36                   ` Marek Behún
2021-10-07 19:25                     ` Bjorn Helgaas
2021-10-01 19:58 ` [PATCH 10/13] PCI: aardvark: Simplify initialization of rootcap on virtual bridge Marek Behún
2021-10-04  9:44   ` Lorenzo Pieralisi
2021-10-04  9:56     ` Marek Behún
2021-10-04 10:10       ` Lorenzo Pieralisi
2021-10-01 19:58 ` [PATCH 11/13] PCI: aardvark: Fix link training Marek Behún
2021-10-01 19:58 ` [PATCH 12/13] PCI: aardvark: Fix checking for link up via LTSSM state Marek Behún
2021-10-04 13:35   ` Lorenzo Pieralisi
2021-10-01 19:58 ` [PATCH 13/13] PCI: aardvark: Fix reporting Data Link Layer Link Active Marek Behún
2021-10-04  9:53 ` [PATCH 00/13] PCI: aardvark controller fixes Lorenzo Pieralisi
2021-10-04 10:40   ` Marek Behún

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