From: Bjorn Helgaas <helgaas@kernel.org>
To: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Cc: "Bjorn Helgaas" <bhelgaas@google.com>,
"Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>,
"Jingoo Han" <jingoohan1@gmail.com>,
"Manivannan Sadhasivam" <manivannan.sadhasivam@linaro.org>,
"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Rob Herring" <robh@kernel.org>,
"Johannes Berg" <johannes@sipsolutions.net>,
"Jeff Johnson" <jjohnson@kernel.org>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-msm@vger.kernel.org, mhi@lists.linux.dev,
linux-wireless@vger.kernel.org, ath11k@lists.infradead.org,
quic_jjohnson@quicinc.com, quic_pyarlaga@quicinc.com,
quic_vbadigan@quicinc.com, quic_vpernami@quicinc.com,
quic_mrana@quicinc.com
Subject: Re: [PATCH 4/8] PCI: dwc: qcom: Update ICC & OPP votes based upon the requested speed
Date: Wed, 19 Feb 2025 12:27:46 -0600 [thread overview]
Message-ID: <20250219182746.GA226108@bhelgaas> (raw)
In-Reply-To: <f0e5efb7-8ea0-a064-21e4-6d7596b1a9ae@oss.qualcomm.com>
On Wed, Feb 19, 2025 at 11:28:47PM +0530, Krishna Chaitanya Chundru wrote:
> On 2/19/2025 3:37 AM, Bjorn Helgaas wrote:
> > On Mon, Feb 17, 2025 at 12:04:11PM +0530, Krishna Chaitanya Chundru wrote:
> > > QCOM PCIe controllers needs to disable ASPM before initiating link
> > > re-train. So as part of pre_bw_scale() disable ASPM and as part of
> > > post_scale_bus_bw() enable ASPM back.
> >
> > s/needs/need/
> >
> > Why does Qcom need to disable ASPM? Is there a PCIe spec restriction
> > about this that should be applied to all PCIe host bridges? Or is
> > this a Qcom defect?
> >
> It is QCOM controller issue, PCIe spec doesn't mention to disable ASPM.
OK. I'm a little concerned that disabling/enabling
PCIE_LINK_STATE_ALL might clobber preferences set by drivers of
downstream devices, but I guess ...
Maybe we could add a comment in the code about this being done to work
around some Qcom issue so that browsers of
pci_enable_link_state_locked() don't get the idea that this needs to
be done generically.
Bjorn
next prev parent reply other threads:[~2025-02-19 18:28 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-17 6:34 [PATCH 0/8] bus: mhi: host: Add support for mhi bus bw Krishna Chaitanya Chundru
2025-02-17 6:34 ` [PATCH 1/8] PCI: update current bus speed as part of pci_bus_add_devices() Krishna Chaitanya Chundru
2025-02-17 6:34 ` [PATCH 2/8] PCI/bwctrl: Add support to scale bandwidth before & after link re-training Krishna Chaitanya Chundru
2025-02-17 9:28 ` Ilpo Järvinen
2025-02-19 17:57 ` Krishna Chaitanya Chundru
2025-02-17 6:34 ` [PATCH 3/8] PCI: dwc: Implement .pre_scale_bus_bw() & .post_scale_bus_bw hook Krishna Chaitanya Chundru
2025-02-17 6:34 ` [PATCH 4/8] PCI: dwc: qcom: Update ICC & OPP votes based upon the requested speed Krishna Chaitanya Chundru
2025-02-18 0:36 ` kernel test robot
2025-02-18 22:07 ` Bjorn Helgaas
2025-02-19 17:58 ` Krishna Chaitanya Chundru
2025-02-19 18:27 ` Bjorn Helgaas [this message]
2025-02-17 6:34 ` [PATCH 5/8] bus: mhi: host: Add support to read MHI capabilities Krishna Chaitanya Chundru
2025-02-17 6:34 ` [PATCH 6/8] bus: mhi: host: Add support for Bandwidth scale Krishna Chaitanya Chundru
2025-02-17 9:17 ` Ilpo Järvinen
2025-02-19 18:02 ` Krishna Chaitanya Chundru
2025-02-17 10:55 ` kernel test robot
2025-02-17 6:34 ` [PATCH 7/8] PCI: Make pcie_link_speed variable public & export pci_set_target_speed() Krishna Chaitanya Chundru
2025-02-19 17:36 ` Jeff Johnson
2025-02-17 6:34 ` [PATCH 8/8] wifi: ath11k: add support for MHI bandwidth scaling Krishna Chaitanya Chundru
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=20250219182746.GA226108@bhelgaas \
--to=helgaas@kernel.org \
--cc=ath11k@lists.infradead.org \
--cc=bhelgaas@google.com \
--cc=ilpo.jarvinen@linux.intel.com \
--cc=jingoohan1@gmail.com \
--cc=jjohnson@kernel.org \
--cc=johannes@sipsolutions.net \
--cc=krishna.chundru@oss.qualcomm.com \
--cc=kw@linux.com \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=linux-wireless@vger.kernel.org \
--cc=lpieralisi@kernel.org \
--cc=manivannan.sadhasivam@linaro.org \
--cc=mhi@lists.linux.dev \
--cc=quic_jjohnson@quicinc.com \
--cc=quic_mrana@quicinc.com \
--cc=quic_pyarlaga@quicinc.com \
--cc=quic_vbadigan@quicinc.com \
--cc=quic_vpernami@quicinc.com \
--cc=robh@kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.