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From: Brian Masney <bmasney@redhat.com>
To: Johan Hovold <johan+linaro@kernel.org>
Cc: "Stanimir Varbanov" <svarbanov@mm-sol.com>,
	"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
	"Andy Gross" <agross@kernel.org>,
	"Bjorn Andersson" <andersson@kernel.org>,
	"Konrad Dybcio" <konrad.dybcio@somainline.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Manivannan Sadhasivam" <mani@kernel.org>,
	"Krishna chaitanya chundru" <quic_krichai@quicinc.com>,
	quic_vbadigan@quicinc.com, linux-arm-msm@vger.kernel.org,
	linux-pci@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] PCI: qcom: Add basic interconnect support
Date: Wed, 19 Oct 2022 10:32:41 -0400	[thread overview]
Message-ID: <Y1AKiTkLa23idaf2@x1> (raw)
In-Reply-To: <20221017112449.2146-3-johan+linaro@kernel.org>

On Mon, Oct 17, 2022 at 01:24:49PM +0200, Johan Hovold wrote:
> +	/*
> +	 * Some Qualcomm platforms require interconnect bandwidth constraints
> +	 * to be set before enabling interconnect clocks.
> +	 *
> +	 * Set an initial peak bandwidth corresponding to single-lane Gen 1
> +	 * for the pcie-mem path.
> +	 */
> +	ret = icc_set_bw(pcie->icc_mem, 0, MBps_to_icc(250));

[snip]

> +	speed = FIELD_GET(PCI_EXP_LNKSTA_CLS, status);
> +	width = FIELD_GET(PCI_EXP_LNKSTA_NLW, status);
> +
> +	switch (speed) {
> +	case 1:
> +		bw = MBps_to_icc(250);
> +		break;
> +	case 2:
> +		bw = MBps_to_icc(500);
> +		break;
> +	default:
> +	case 3:
> +		bw = MBps_to_icc(985);
> +		break;
> +	}

Just curious: These platforms have a 4 lane PCIe bus. Why use 985
instead of 1000 for the maximum?

Brian


  reply	other threads:[~2022-10-19 14:46 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-17 11:24 [PATCH 0/2] PCI: qcom: Add basic interconnect support Johan Hovold
2022-10-17 11:24 ` [PATCH 1/2] dt-bindings: PCI: qcom: Add SC8280XP/SA8540P interconnects Johan Hovold
2022-10-19 14:37   ` Krzysztof Kozlowski
2022-10-20  7:57     ` Johan Hovold
2022-10-20 12:29       ` Krzysztof Kozlowski
2022-10-21  6:40         ` Johan Hovold
2022-10-17 11:24 ` [PATCH 2/2] PCI: qcom: Add basic interconnect support Johan Hovold
2022-10-19 14:32   ` Brian Masney [this message]
2022-10-19 14:45     ` Johan Hovold
2022-10-20 16:49   ` Brian Masney

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