From: Stanimir Varbanov <svarbanov@mm-sol.com>
To: Bjorn Andersson <bjorn.andersson@linaro.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org, linux-arm-msm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Khasim Syed Mohammed <khasim.mohammed@linaro.org>,
Niklas Cassel <niklas.cassel@linaro.org>,
stable@vger.kernel.org
Subject: Re: [PATCH] PCI: qcom: Don't deassert reset GPIO during probe
Date: Fri, 8 Feb 2019 16:54:44 +0200 [thread overview]
Message-ID: <d972ef33-5069-e012-abd5-31f2f985af6d@mm-sol.com> (raw)
In-Reply-To: <20190125232616.25714-1-bjorn.andersson@linaro.org>
Hi Bjorn,
Thanks for the patch!
On 1/26/19 1:26 AM, Bjorn Andersson wrote:
> Acquiring the reset GPIO low means that reset is being deasserted, this
> is followed almost immediately with qcom_pcie_host_init() asserting it,
> initializing it and then finally deasserting it again, for the link to
> come up.
>
> Some PCIe devices requires a minimum time between the initial deassert
> and subsequent reset cycles. In a platform that boots with the reset
> GPIO asserted this requirement is being violated by this deassert/assert
> pulse.
>
> Acquiring the reset GPIO high will prevent this by matching the state to
> the subsequent asserted state.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
> drivers/pci/controller/dwc/pcie-qcom.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index d185ea5fe996..a7f703556790 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -1228,7 +1228,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
>
> pcie->ops = of_device_get_match_data(dev);
>
> - pcie->reset = devm_gpiod_get_optional(dev, "perst", GPIOD_OUT_LOW);
> + pcie->reset = devm_gpiod_get_optional(dev, "perst", GPIOD_OUT_HIGH);
> if (IS_ERR(pcie->reset)) {
> ret = PTR_ERR(pcie->reset);
> goto err_pm_runtime_put;
>
Acked-by: Stanimir Varbanov <svarbanov@mm-sol.com>
--
regards,
Stan
next prev parent reply other threads:[~2019-02-08 15:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-25 23:26 [PATCH] PCI: qcom: Don't deassert reset GPIO during probe Bjorn Andersson
2019-02-08 14:54 ` Stanimir Varbanov [this message]
2019-02-13 15:23 ` Lorenzo Pieralisi
2019-02-19 5:16 ` Bjorn Andersson
2019-02-19 11:10 ` Lorenzo Pieralisi
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