From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
To: Dilip Kota <eswara.kota@linux.intel.com>
Cc: "Chuan Hua, Lei" <chuanhua.lei@linux.intel.com>,
andriy.shevchenko@intel.com, cheol.yong.kim@intel.com,
devicetree@vger.kernel.org, gustavo.pimentel@synopsys.com,
hch@infradead.org, jingoohan1@gmail.com,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
qi-ming.wu@intel.com
Subject: Re: [PATCH v2 3/3] dwc: PCI: intel: Intel PCIe RC controller driver
Date: Tue, 27 Aug 2019 22:51:12 +0200 [thread overview]
Message-ID: <CAFBinCDgpNMfF-DnZSLAd7Ps66OKnUdpDmi7OE2O0bctOwwvCg@mail.gmail.com> (raw)
In-Reply-To: <e4ddb571-e003-7bb8-a04c-795423ea0e2f@linux.intel.com>
Hi Dilip,
On Tue, Aug 27, 2019 at 10:47 AM Dilip Kota <eswara.kota@linux.intel.com> wrote:
[...]
> >
> >
> >> now I am wondering:
> >> - if we don't have to disable the interrupt line (once it is enabled),
> >> why can't we enable all of these interrupts at initialization time
> >> (instead of doing it on-demand)?
> > Good point! we even can remote map_irq patch, directly call
> >
> > of_irq_parse_and_map_pci as other drivers do.
>
> Irrespective of disabling, imo interrupts(A/B/C/D) should be enabled
> when they are requested; which happens during map_irq() call.
with an integrated interrupt controller (which I decided to use in my
experiment because I could not find a .unmap_irq callback) this would
be the case:
- of_irq_parse_and_map_pci finds our APP interrupt
- this will enable the interrupt in the PCIe controller's APP register first
- then it will enable the interrupt in the parent interrupt controller
- when the PCIe card then frees the IRQ line again we will disable
both interrupts (the APP interrupt as well as the parent interrupt)
I don't see why of_irq_parse_and_map_pci + custom code to enable the
APP interrupt in .map_irq (without any .unmap_irq callback) is better
than always enabling it
[...]
> >>> This is needed. In the old driver, we fixed this by fixup. The original
> >>> comment as follows,
> >>>
> >>> /*
> >>> * The root complex has a hardwired class of
> >>> PCI_CLASS_NETWORK_OTHER or
> >>> * PCI_CLASS_BRIDGE_HOST, when it is operating as a root complex this
> >>> * needs to be switched to * PCI_CLASS_BRIDGE_PCI
> >>> */
> >> that would be a good comment to add if you really need it
> >> can you please look at dw_pcie_setup_rc (from
> >> pcie-designware-host.c), it does:
> >> /* Enable write permission for the DBI read-only register */
> >> dw_pcie_dbi_ro_wr_en(pci);
> >> /* Program correct class for RC */
> >> dw_pcie_wr_own_conf(pp, PCI_CLASS_DEVICE, 2, PCI_CLASS_BRIDGE_PCI);
> >> /* Better disable write permission right after the update */
> >> dw_pcie_dbi_ro_wr_dis(pci);
> >>
> >> so my understanding is that there is a functional requirement to set
> >> the class to PCI_CLASS_BRIDGE_PCI
> >> however, that requirement is already covered by pcie-designware-host.c
> > I will task Dilip to check if we can use dwc one.
> dw_pcie_setup_rc () cannot be called here because, it is not doing
> PCI_CLASS_BRIDGE_PCI set alone, it is configuring many other things.
I am surprised to see that dw_pcie_setup_rc() is not used at all in your driver
it sets up BARs, bus numbers, interrupt pins, the command register, etc.
with my limited knowledge I assumed that these ("many other things")
are all mandatory so everything works correctly
what problems do you experience when you use dw_pcie_setup_rc()?
also it seems that virtually every PCIe driver based on the DWC
controller uses it:
$ grep -R dw_pcie_setup_rc drivers/pci/controller/dwc/ | wc -l
20
Martin
next prev parent reply other threads:[~2019-08-27 20:51 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-20 9:39 [PATCH v2 0/3] PCI: Add map irq callback in dwc framework and add Intel PCIe driver Dilip Kota
2019-08-20 9:39 ` [PATCH v2 1/3] PCI: dwc: Add map irq callback Dilip Kota
2019-08-20 9:39 ` [PATCH v2 2/3] dt-bindings: PCI: intel: Add YAML schemas for the PCIe RC controller Dilip Kota
2019-08-20 13:42 ` Rob Herring
2019-08-21 9:56 ` Dilip Kota
2019-08-20 9:39 ` [PATCH v2 3/3] dwc: PCI: intel: Intel PCIe RC controller driver Dilip Kota
2019-08-24 21:03 ` Martin Blumenstingl
2019-08-26 3:30 ` Chuan Hua, Lei
2019-08-26 6:48 ` Dilip Kota
[not found] ` <f1cb5ba9-b57a-971a-5a2f-1f13e0cc9507@linux.intel.com>
2019-08-26 20:14 ` Martin Blumenstingl
2019-08-27 9:14 ` Dilip Kota
2019-08-26 21:15 ` Martin Blumenstingl
2019-08-27 3:09 ` Chuan Hua, Lei
2019-08-27 8:47 ` Dilip Kota
2019-08-27 20:51 ` Martin Blumenstingl [this message]
2019-08-27 20:38 ` Martin Blumenstingl
2019-08-28 3:35 ` Chuan Hua, Lei
2019-08-28 19:36 ` Martin Blumenstingl
2019-08-29 2:54 ` Chuan Hua, Lei
[not found] ` <4bab775a-0e39-a187-0791-40050feb7d67@linux.intel.com>
2019-09-03 18:36 ` Martin Blumenstingl
2019-08-29 5:10 ` Kishon Vijay Abraham I
2019-08-29 21:01 ` Martin Blumenstingl
2019-08-27 14:28 ` Andy Shevchenko
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