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Date: Tue, 9 Apr 2024 16:33:34 +0530
From: Varadarajan Narayanan <quic_varada@quicinc.com>
To: Krzysztof Kozlowski <krzk@kernel.org>
CC: <andersson@kernel.org>, <konrad.dybcio@linaro.org>,
        <mturquette@baylibre.com>, <sboyd@kernel.org>, <robh@kernel.org>,
        <krzk+dt@kernel.org>, <conor+dt@kernel.org>, <djakov@kernel.org>,
        <dmitry.baryshkov@linaro.org>, <quic_anusha@quicinc.com>,
        <linux-arm-msm@vger.kernel.org>, <linux-clk@vger.kernel.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-pm@vger.kernel.org>
Subject: Re: [PATCH v7 1/5] dt-bindings: interconnect: Add Qualcomm IPQ9574
 support
Message-ID: <ZhUghsa5Do5m7wrX@hu-varada-blr.qualcomm.com>
References: <20240403104220.1092431-1-quic_varada@quicinc.com>
 <20240403104220.1092431-2-quic_varada@quicinc.com>
 <58c9b754-b9a7-444d-9545-9e6648010630@kernel.org>
 <Zg5q6mnWtK6hmPBT@hu-varada-blr.qualcomm.com>
 <ZhTxFVDH0xTSkw7r@hu-varada-blr.qualcomm.com>
 <1ec401be-11cb-416a-9eae-d72ea8acf06f@kernel.org>
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On Tue, Apr 09, 2024 at 11:45:51AM +0200, Krzysztof Kozlowski wrote:
> On 09/04/2024 09:41, Varadarajan Narayanan wrote:
> > On Thu, Apr 04, 2024 at 02:25:06PM +0530, Varadarajan Narayanan wrote:
> >> On Wed, Apr 03, 2024 at 04:59:40PM +0200, Krzysztof Kozlowski wrote:
> >>> On 03/04/2024 12:42, Varadarajan Narayanan wrote:
> >>>> Add interconnect-cells to clock provider so that it can be
> >>>> used as icc provider.
> >>>>
> >>>> Add master/slave ids for Qualcomm IPQ9574 Network-On-Chip
> >>>> interfaces. This will be used by the gcc-ipq9574 driver
> >>>> that will for providing interconnect services using the
> >>>> icc-clk framework.
> >>>>
> >>>> Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
> >>>> ---
> >>>> v7:
> >>>> Fix macro names to be consistent with other bindings
> >>>> v6:
> >>>> Removed Reviewed-by: Krzysztof Kozlowski
> >>>> Redefine the bindings such that driver and DT can share them
> >>>>
> >>>> v3:
> >>>> Squash Documentation/ and include/ changes into same patch
> >>>>
> >>>> qcom,ipq9574.h
> >>>> 	Move 'first id' to clock driver
> >>>>
> >>>> ---
> >>>>  .../bindings/clock/qcom,ipq9574-gcc.yaml      |  3 +
> >>>>  .../dt-bindings/interconnect/qcom,ipq9574.h   | 87 +++++++++++++++++++
> >>>>  2 files changed, 90 insertions(+)
> >>>>  create mode 100644 include/dt-bindings/interconnect/qcom,ipq9574.h
> >>>>
> >>>> diff --git a/Documentation/devicetree/bindings/clock/qcom,ipq9574-gcc.yaml b/Documentation/devicetree/bindings/clock/qcom,ipq9574-gcc.yaml
> >>>> index 944a0ea79cd6..824781cbdf34 100644
> >>>> --- a/Documentation/devicetree/bindings/clock/qcom,ipq9574-gcc.yaml
> >>>> +++ b/Documentation/devicetree/bindings/clock/qcom,ipq9574-gcc.yaml
> >>>> @@ -33,6 +33,9 @@ properties:
> >>>>        - description: PCIE30 PHY3 pipe clock source
> >>>>        - description: USB3 PHY pipe clock source
> >>>>
> >>>> +  '#interconnect-cells':
> >>>> +    const: 1
> >>>> +
> >>>>  required:
> >>>>    - compatible
> >>>>    - clocks
> >>>> diff --git a/include/dt-bindings/interconnect/qcom,ipq9574.h b/include/dt-bindings/interconnect/qcom,ipq9574.h
> >>>> new file mode 100644
> >>>> index 000000000000..0b076b0cf880
> >>>> --- /dev/null
> >>>> +++ b/include/dt-bindings/interconnect/qcom,ipq9574.h
> >>>> @@ -0,0 +1,87 @@
> >>>> +/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
> >>>> +#ifndef INTERCONNECT_QCOM_IPQ9574_H
> >>>> +#define INTERCONNECT_QCOM_IPQ9574_H
> >>>> +
> >>>> +#define ICC_ANOC_PCIE0		0
> >>>> +#define ICC_SNOC_PCIE0		1
> >>>> +#define ICC_ANOC_PCIE1		2
> >>>> +#define ICC_SNOC_PCIE1		3
> >>>> +#define ICC_ANOC_PCIE2		4
> >>>> +#define ICC_SNOC_PCIE2		5
> >>>> +#define ICC_ANOC_PCIE3		6
> >>>> +#define ICC_SNOC_PCIE3		7
> >>>> +#define ICC_SNOC_USB		8
> >>>> +#define ICC_ANOC_USB_AXI	9
> >>>> +#define ICC_NSSNOC_NSSCC	10
> >>>> +#define ICC_NSSNOC_SNOC_0	11
> >>>> +#define ICC_NSSNOC_SNOC_1	12
> >>>> +#define ICC_NSSNOC_PCNOC_1	13
> >>>> +#define ICC_NSSNOC_QOSGEN_REF	14
> >>>> +#define ICC_NSSNOC_TIMEOUT_REF	15
> >>>> +#define ICC_NSSNOC_XO_DCD	16
> >>>> +#define ICC_NSSNOC_ATB		17
> >>>> +#define ICC_MEM_NOC_NSSNOC	18
> >>>> +#define ICC_NSSNOC_MEMNOC	19
> >>>> +#define ICC_NSSNOC_MEM_NOC_1	20
> >>>> +
> >>>> +#define ICC_NSSNOC_PPE		0
> >>>> +#define ICC_NSSNOC_PPE_CFG	1
> >>>> +#define ICC_NSSNOC_NSS_CSR	2
> >>>> +#define ICC_NSSNOC_IMEM_QSB	3
> >>>> +#define ICC_NSSNOC_IMEM_AHB	4
> >>>> +
> >>>> +#define MASTER_ANOC_PCIE0		(ICC_ANOC_PCIE0 * 2)
> >>>> +#define SLAVE_ANOC_PCIE0		((ICC_ANOC_PCIE0 * 2) + 1)
> >>>
> >>> Which existing Qualcomm platform has such code?
> >>
> >> Existing Qualcomm platforms don't use icc-clk. They use icc-rpm
> >> or icc-rpmh. clk-cbf-msm8996.c is the only driver that uses icc-clk.
> >>
> >> The icc_clk_register automatically creates master & slave nodes
> >> for each clk entry provided as input with the node-ids 'n' and
> >> 'n+1'. Since clk-cbf-msm8996.c has only one entry, it could just
> >> define MASTER_CBF_M4M and SLAVE_CBF_M4M with 0 and 1 and avoid these
> >> calculations.
> >>
> >> However, ipq9574 gives an array of clock entries as input to
> >> icc_clk_register. To tie the order/sequence of these clock
> >> entries correctly with the node-ids, this calculation is needed.
> >>
> >>> This is the third time I am asking for consistent headers. Open
> >>> existing, recently added headers and look how it is done there. Why?
> >>> Because I am against such calculations and see no reason for them.
> >>
> >> Apologies. Regret that I have to trouble you.
> >>
> >> In this ipq9574 case, have to reconcile between the following
> >> feedbacks.
> >>
> >> 1. https://lore.kernel.org/linux-arm-msm/fe40b307-26d0-4b2a-869b-5d093415b9d1@linaro.org/
> >>    We could probably use indexed identifiers here to avoid confusion:
> >>    [ICC_BINDING_NAME] = CLK_BINDING_NAME
> >>
> >> 2. https://lore.kernel.org/linux-arm-msm/95f4e99a60cc97770fc3cee850b62faf.sboyd@kernel.org/
> >>    Are these supposed to be in a dt-binding header?
> >>
> >> 3. https://lore.kernel.org/linux-arm-msm/031d0a35-b192-4161-beef-97b89d5d1da6@linaro.org/
> >>    Do you use them as well in the DTS?
> >>
> >> Having the defines (with the calculations) seemed to to comply
> >> with the above three feedbacks.
> >>
> >> Please let me know if this can be handled in a different way that
> >> would be consistent with other Qualcomm platforms.
> >
> > Krzysztof,
> >
> > Is this ok? Can I post a new version addressing other review comments?
>
> I don't understand and you did not answered before, why you have to do
> it differently than all other Qualcomm interconnect providers. Maybe the
> code here needs it, maybe not, but I don't see any argument proving this.

Other Qualcomm interconnect providers use the icc-rpm.

	1. The SoC specific interconnect providers have control
	   over the master/slave id-numbers and is hard coded.

	2. These id-numbers are used by the RPM firmware.

IPQ9574 uses icc-clk.

	1. The ipq9574 specific interconnect provider doesn't
	   have control over the master/slave id-numbers. The
	   icc-clk framework auto generates it in the order of
	   the clock entries given as input.

	2. These auto-generated id-numbers have to be correctly
	   tied to the DT nodes. Else, the relevant clocks may
	   not get enabled.

Since ICC-CLK creates two ids per clock entry (one MASTER_xxx and
one SLAVE_xxx), using those MASTER/SLAVE_xxx macros as indices in
the below array would create holes.

	static int icc_ipq9574_hws[] = {
		[MASTER_ANOC_PCIE0] = GCC_ANOC_PCIE0_1LANE_M_CLK,
		[MASTER_SNOC_PCIE0] = GCC_SNOC_PCIE0_1LANE_S_CLK,
		[MASTER_ANOC_PCIE1] = GCC_ANOC_PCIE1_1LANE_M_CLK,
		[MASTER_SNOC_PCIE1] = GCC_SNOC_PCIE1_1LANE_S_CLK,
		. . .
	};

Other Qualcomm drivers don't have this issue and they can
directly use the MASTER/SLAVE_xxx macros.

As the MASTER_xxx macros cannot be used, have to define a new set
of macros that can be used for indices in the above array. This
is the reason for the ICC_BINDING_NAME macros.

Does this answer your concern? Please let me know.

Thanks
Varada