Re: [PATCH RESEND v4 03/15] PCI: dwc: Convert to using native IP-core versions representation

From: Bjorn Helgaas <helgaas@kernel.org>
To: Ben Dooks <ben.dooks@codethink.co.uk>
Cc: "Serge Semin" <Sergey.Semin@baikalelectronics.ru>,
	"Rob Herring" <robh@kernel.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
	"Jingoo Han" <jingoohan1@gmail.com>,
	"Gustavo Pimentel" <gustavo.pimentel@synopsys.com>,
	"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Rahul Tanwar" <rtanwar@maxlinear.com>,
	"Thierry Reding" <thierry.reding@gmail.com>,
	"Jonathan Hunter" <jonathanh@nvidia.com>,
	"Serge Semin" <fancer.lancer@gmail.com>,
	"Alexey Malahov" <Alexey.Malahov@baikalelectronics.ru>,
	"Pavel Parkhomenko" <Pavel.Parkhomenko@baikalelectronics.ru>,
	"Frank Li" <Frank.Li@nxp.com>,
	"Manivannan Sadhasivam" <manivannan.sadhasivam@linaro.org>,
	"Rob Herring" <robh+dt@kernel.org>,
	linux-pci@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org
Subject: Re: [PATCH RESEND v4 03/15] PCI: dwc: Convert to using native IP-core versions representation
Date: Thu, 28 Jul 2022 11:34:28 -0500	[thread overview]
Message-ID: <20220728163428.GA309179@bhelgaas> (raw)
In-Reply-To: <0d644682-094d-6151-aa2f-86552c8f9a87@codethink.co.uk>

On Thu, Jul 28, 2022 at 04:31:17PM +0100, Ben Dooks wrote:
> On 28/07/2022 16:24, Bjorn Helgaas wrote:
> > On Fri, Jun 24, 2022 at 05:39:35PM +0300, Serge Semin wrote:
> > > Since DWC PCIe v4.70a the controller version can be read from the
> > > PORT_LOGIC.PCIE_VERSION_OFF register. Version is represented in the FourCC
> > > format [1]. It's standard versioning approach for the Synopsys DWC
> > > IP-cores. Moreover some of the DWC kernel drivers already make use of it
> > > to fixup version-dependent functionality (See DWC USB3, Stmicro STMMAC or
> > > recent DW SPI driver).
> > 
> > These references to other drivers might be useful, but without a
> > function name or file name, I can't easily find them.
> > 
> > > In order to preserve the standard version
> > > representation and prevent the data conversion back and forth, we suggest
> > > to preserve the native version representation in the DWC PCIe driver too
> > > in the same way as it has already been done in the rest of the DWC
> > > drivers. IP-core version reading from the CSR will be introduced in the
> > > next commit together with a simple macro-based API to use it.
> > > 
> > > [1] https://en.wikipedia.org/wiki/FourCC
> 
> I'm currently looking at a OF based dw-apb-timers-pwm driver, so also
> would like to follow this.

FWIW, the breadcrumbs I found are:

  dwc3_core_is_valid()
  stmmac_hwif_init()
  dw_spi_hw_init()