From: Bjorn Helgaas <helgaas@kernel.org>
To: Vidya Sagar <vidyas@nvidia.com>
Cc: jingoohan1@gmail.com, gustavo.pimentel@synopsys.com,
lpieralisi@kernel.org, robh@kernel.org, kw@linux.com,
bhelgaas@google.com, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org, kthota@nvidia.com,
mmaddireddy@nvidia.com, sagar.tv@gmail.com
Subject: Re: [PATCH V1] PCI: designware-ep: Fix DBI access before core init
Date: Thu, 28 Jul 2022 09:17:16 -0500 [thread overview]
Message-ID: <20220728141716.GA296915@bhelgaas> (raw)
In-Reply-To: <051a3baf-b4dd-7764-2e61-03584cefb4d3@nvidia.com>
On Thu, Jul 28, 2022 at 05:56:28PM +0530, Vidya Sagar wrote:
>
>
> On 7/28/2022 3:44 AM, Bjorn Helgaas wrote:
> > External email: Use caution opening links or attachments
> >
> >
> > On Wed, Jun 22, 2022 at 09:31:33AM +0530, Vidya Sagar wrote:
> > > Platforms that cannot support their core initialization without the
> > > reference clock from the host, implement the feature 'core_init_notifier'
> > > to indicate the DesignWare sub-system about when their core is getting
> > > initialized. Any accesses to the core (Ex:- DBI) would result in system
> > > hang in such systems (Ex:- tegra194). This patch moves any access to the
> > > core to dw_pcie_ep_init_complete() API which is effectively called only
> > > after the core initialization.
> >
> > I assume this is still broken. I want to fix it. I assume this patch
> > fixes it and there are no known problems with it. I assume this can
> > be fixed so it works on all platforms, whether they use
> > core_init_notifier or not.
> Yes. All your assumptions are correct.
>
> >
> > I'd like the commit log to be specific about where the hang occurs so
> > it's easy for a non-DesignWare expert (me!) to see the problem. E.g.,
> > on tegra194, X depends on Y, but Y is initialized after X. Say
> > specifically what functions X and Y are.
> X = DBI accesses
> Y = Core initialization which in turn depends on the REFCLK from the host
>
> Without this patch, hang happens when DBI registers are accessed without
> core being initialized. In the case of Tegra194 at least, core gets
> initialized only after REFCLK is available from the host. The way we make
> sure that the REFCLK is available from the host is by checking for PERST#
> de-assertion interrupt. (PCIe spec mandates that the host must supply REFCLK
> before de-asserting PERST# signal).
> This patch prevents any accesses to the DBI/Core registers if the platform
> says that it supports core_init_notifier.
That's basically what the commit log already said. Can you give me
actual function names as a hint for where to look?
Bjorn
next prev parent reply other threads:[~2022-07-28 14:17 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-22 4:01 [PATCH V1] PCI: designware-ep: Fix DBI access before core init Vidya Sagar
2022-07-07 9:09 ` Vidya Sagar
2022-07-07 16:00 ` Bjorn Helgaas
2022-07-07 16:31 ` Vidya Sagar
2022-07-07 16:55 ` Manivannan Sadhasivam
2022-07-27 22:14 ` Bjorn Helgaas
2022-07-28 12:26 ` Vidya Sagar
2022-07-28 14:17 ` Bjorn Helgaas [this message]
2022-07-29 22:44 ` Bjorn Helgaas
2022-07-30 14:50 ` Manivannan Sadhasivam
2022-08-01 20:27 ` Rob Herring
2022-08-02 7:24 ` Manivannan Sadhasivam
2022-08-02 14:07 ` Manivannan Sadhasivam
2022-08-10 18:16 ` Rob Herring
2022-08-16 14:15 ` Lorenzo Pieralisi
2022-08-16 14:35 ` Vidya Sagar
2022-08-19 8:35 ` Manivannan Sadhasivam
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220728141716.GA296915@bhelgaas \
--to=helgaas@kernel.org \
--cc=bhelgaas@google.com \
--cc=gustavo.pimentel@synopsys.com \
--cc=jingoohan1@gmail.com \
--cc=kthota@nvidia.com \
--cc=kw@linux.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=lpieralisi@kernel.org \
--cc=mmaddireddy@nvidia.com \
--cc=robh@kernel.org \
--cc=sagar.tv@gmail.com \
--cc=vidyas@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).