Re: [PATCH RESEND v4 14/15] PCI: dwc: Check iATU in/outbound ranges setup methods status

From: Bjorn Helgaas <helgaas@kernel.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
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>,
	"Serge Semin" <fancer.lancer@gmail.com>,
	"Alexey Malahov" <Alexey.Malahov@baikalelectronics.ru>,
	"Pavel Parkhomenko" <Pavel.Parkhomenko@baikalelectronics.ru>,
	"Frank Li" <Frank.Li@nxp.com>, "Rob Herring" <robh+dt@kernel.org>,
	linux-pci@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH RESEND v4 14/15] PCI: dwc: Check iATU in/outbound ranges setup methods status
Date: Mon, 1 Aug 2022 15:17:24 -0500	[thread overview]
Message-ID: <20220801201724.GA623582@bhelgaas> (raw)
In-Reply-To: <20220801135457.GN93763@thinkpad>

On Mon, Aug 01, 2022 at 07:24:57PM +0530, Manivannan Sadhasivam wrote:
> On Fri, Jun 24, 2022 at 05:39:46PM +0300, Serge Semin wrote:
> > Let's make the DWC PCIe RC/EP safer and more verbose for the invalid or
> > failed inbound and outbound iATU windows setups. Needless to say that
> > silently ignoring iATU regions setup errors may cause unpredictable
> > errors. For instance if for some reason a cfg or IO window fails to be
> > activated, then any CFG/IO requested won't reach target PCIe devices and
> > the corresponding accessors will return platform-specific random values.
> > 
> > First of all we need to convert dw_pcie_ep_outbound_atu() method to check
> > whether the specified outbound iATU range is successfully setup. That
> > method is called by the pci_epc_ops.map_addr callback. Thus we'll make the
> > EP-specific CPU->PCIe memory mappings saver.
> > 
> > Secondly since the iATU outbound range programming method now returns the
> > operation status, it will be handy to take that status into account in the
> > pci_ops.{map_bus,read,write} methods. Thus any failed mapping will be
> > immediately noticeable by the PCIe CFG operations requesters.
> > 
> > Finally we need to convert the dw_pcie_setup_rc() method to returning the
> > operation status, since the iATU outbound ranges setup procedure may now
> > fail. It will be especially handy in case if the DW PCIe RC DT-node has
> > invalid/unsupported (dma-)ranges property. Note since the suggested
> > modification causes having too wide code indentation, it is reasonable
> > from maintainability and readability points of view to move the outbound
> > ranges setup procedure in the separate function.
> > 
> > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> 
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Thank you very much for all your reviews, Manivannan!  I added your
reviewed-by to the appropriate commits.