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From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
	Lee Jones <lee.jones@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Alim Akhtar <alim.akhtar@samsung.com>,
	Dinh Nguyen <dinguyen@kernel.org>,
	Michal Simek <michal.simek@xilinx.com>,
	Liviu Dudau <liviu.dudau@arm.com>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Ray Jui <rjui@broadcom.com>,
	Scott Branden <sbranden@broadcom.com>,
	Broadcom Kernel Team <bcm-kernel-feedback-list@broadcom.com>,
	Sylwester Nawrocki <s.nawrocki@samsung.com>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Rob Herring <robh@kernel.org>
Subject: Re: [PATCH 08/10] ARM: dts: exynos: use proper 'dma-channels/requests' properties
Date: Thu, 28 Apr 2022 12:05:33 +0200	[thread overview]
Message-ID: <99c80fb6-c6cc-9370-b93d-ed736c7f2192@samsung.com> (raw)
In-Reply-To: <1399774c-f188-81f1-4d15-367b9d0e4a59@linaro.org>

On 28.04.2022 12:00, Krzysztof Kozlowski wrote:
> On 28/04/2022 11:57, Marek Szyprowski wrote:
>> On 28.04.2022 11:54, Krzysztof Kozlowski wrote:
>>> On 28/04/2022 11:50, Marek Szyprowski wrote:
>>>> On 27.04.2022 17:58, Krzysztof Kozlowski wrote:
>>>>> pl330 DMA controller bindings documented 'dma-channels' and
>>>>> 'dma-requests' properties (without leading hash sign), so fix the DTS to
>>>>> match the bindings.
>>>>>
>>>>> Reported-by: Rob Herring <robh@kernel.org>
>>>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>>> Are those properties really needed for PL330 driver on Exynos SoCs? I've
>>>> removed them and I still see the proper values read from registers and
>>>> reported in the log (Exynos4210):
>>>>
>>>> dma-pl330 12680000.dma-controller: Loaded driver for PL330 DMAC-141330
>>>> dma-pl330 12680000.dma-controller:       DBUFF-32x4bytes Num_Chans-8
>>>> Num_Peri-32 Num_Events-32
>>>> dma-pl330 12690000.dma-controller: Loaded driver for PL330 DMAC-141330
>>>> dma-pl330 12690000.dma-controller:       DBUFF-32x4bytes Num_Chans-8
>>>> Num_Peri-32 Num_Events-32
>>>> dma-pl330 12850000.dma-controller: Loaded driver for PL330 DMAC-141330
>>>> dma-pl330 12850000.dma-controller:       DBUFF-64x8bytes Num_Chans-8
>>>> Num_Peri-1 Num_Events-32
>>>>
>>>> I also don't see any code that would read those properties. IMHO they
>>>> should be simply removed at all, at least for the PL330 related nodes.
>>> In current Linux implementation they indeed are not used. Nothing parses
>>> them. However:
>>> 1. They describe (hopefully correct) the hardware.
>>> 2. They might be used by other implementations of pl330 driver.
>>>
>>> I would not remove them from existing sources, but indeed maybe there is
>>> no need to add for new files.
>> What's the point in having dt properties duplicating data that might be
>> read from the driver registers?
> Hm, indeed, there is no point in this. Since they are read from
> registers, what was the idea behind in commit 42cf20980cde?

#dma-cells is indeed required, but the rest seems to be the cargo-cult 
of some kind.


Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland


WARNING: multiple messages have this Message-ID
From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
	Lee Jones <lee.jones@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Alim Akhtar <alim.akhtar@samsung.com>,
	Dinh Nguyen <dinguyen@kernel.org>,
	Michal Simek <michal.simek@xilinx.com>,
	Liviu Dudau <liviu.dudau@arm.com>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Ray Jui <rjui@broadcom.com>,
	Scott Branden <sbranden@broadcom.com>,
	Broadcom Kernel Team <bcm-kernel-feedback-list@broadcom.com>,
	Sylwester Nawrocki <s.nawrocki@samsung.com>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Rob Herring <robh@kernel.org>
Subject: Re: [PATCH 08/10] ARM: dts: exynos: use proper 'dma-channels/requests' properties
Date: Thu, 28 Apr 2022 12:05:33 +0200	[thread overview]
Message-ID: <99c80fb6-c6cc-9370-b93d-ed736c7f2192@samsung.com> (raw)
In-Reply-To: <1399774c-f188-81f1-4d15-367b9d0e4a59@linaro.org>

On 28.04.2022 12:00, Krzysztof Kozlowski wrote:
> On 28/04/2022 11:57, Marek Szyprowski wrote:
>> On 28.04.2022 11:54, Krzysztof Kozlowski wrote:
>>> On 28/04/2022 11:50, Marek Szyprowski wrote:
>>>> On 27.04.2022 17:58, Krzysztof Kozlowski wrote:
>>>>> pl330 DMA controller bindings documented 'dma-channels' and
>>>>> 'dma-requests' properties (without leading hash sign), so fix the DTS to
>>>>> match the bindings.
>>>>>
>>>>> Reported-by: Rob Herring <robh@kernel.org>
>>>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>>> Are those properties really needed for PL330 driver on Exynos SoCs? I've
>>>> removed them and I still see the proper values read from registers and
>>>> reported in the log (Exynos4210):
>>>>
>>>> dma-pl330 12680000.dma-controller: Loaded driver for PL330 DMAC-141330
>>>> dma-pl330 12680000.dma-controller:       DBUFF-32x4bytes Num_Chans-8
>>>> Num_Peri-32 Num_Events-32
>>>> dma-pl330 12690000.dma-controller: Loaded driver for PL330 DMAC-141330
>>>> dma-pl330 12690000.dma-controller:       DBUFF-32x4bytes Num_Chans-8
>>>> Num_Peri-32 Num_Events-32
>>>> dma-pl330 12850000.dma-controller: Loaded driver for PL330 DMAC-141330
>>>> dma-pl330 12850000.dma-controller:       DBUFF-64x8bytes Num_Chans-8
>>>> Num_Peri-1 Num_Events-32
>>>>
>>>> I also don't see any code that would read those properties. IMHO they
>>>> should be simply removed at all, at least for the PL330 related nodes.
>>> In current Linux implementation they indeed are not used. Nothing parses
>>> them. However:
>>> 1. They describe (hopefully correct) the hardware.
>>> 2. They might be used by other implementations of pl330 driver.
>>>
>>> I would not remove them from existing sources, but indeed maybe there is
>>> no need to add for new files.
>> What's the point in having dt properties duplicating data that might be
>> read from the driver registers?
> Hm, indeed, there is no point in this. Since they are read from
> registers, what was the idea behind in commit 42cf20980cde?

#dma-cells is indeed required, but the rest seems to be the cargo-cult 
of some kind.


Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2022-04-28 10:11 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-27 15:58 [PATCH 00/10] ARM/arm64: dts: use proper 'dma-channels/requests' properties Krzysztof Kozlowski
2022-04-27 15:58 ` Krzysztof Kozlowski
2022-04-27 15:58 ` [PATCH 01/10] ARM: dts: zynq-7000: " Krzysztof Kozlowski
2022-04-27 15:58   ` Krzysztof Kozlowski
2022-04-28  6:24   ` Michal Simek
2022-04-28  6:24     ` Michal Simek
2022-04-27 15:58 ` [PATCH 02/10] ARM: dts: socfpga: " Krzysztof Kozlowski
2022-04-27 15:58   ` Krzysztof Kozlowski
2022-04-27 15:58 ` [PATCH 03/10] arm64: dts: stratix10/agilex: " Krzysztof Kozlowski
2022-04-27 15:58   ` Krzysztof Kozlowski
2022-04-27 15:58 ` [PATCH 04/10] arm64: dts: juno: " Krzysztof Kozlowski
2022-04-27 15:58   ` Krzysztof Kozlowski
2022-04-28 10:43   ` Robin Murphy
2022-04-28 10:43     ` Robin Murphy
2022-04-28 10:45     ` Krzysztof Kozlowski
2022-04-28 10:45       ` Krzysztof Kozlowski
2022-04-27 15:58 ` [PATCH 05/10] arm64: dts: broadcom: " Krzysztof Kozlowski
2022-04-27 15:58   ` Krzysztof Kozlowski
2022-04-27 15:58 ` [PATCH 06/10] dt-bindings: mfd: samsung,exynos5433-lpass: fix " Krzysztof Kozlowski
2022-04-27 15:58   ` [PATCH 06/10] dt-bindings: mfd: samsung, exynos5433-lpass: " Krzysztof Kozlowski
2022-04-27 16:41   ` [PATCH 06/10] dt-bindings: mfd: samsung,exynos5433-lpass: " Alim Akhtar
2022-04-27 16:41     ` Alim Akhtar
2022-04-27 18:25   ` Rob Herring
2022-04-27 18:25     ` Rob Herring
2022-04-28  9:53   ` Lee Jones
2022-04-28  9:53     ` Lee Jones
2022-04-27 15:58 ` [PATCH 07/10] ARM: dts: s5pv210: use proper " Krzysztof Kozlowski
2022-04-27 15:58   ` Krzysztof Kozlowski
2022-04-27 16:45   ` Alim Akhtar
2022-04-27 16:45     ` Alim Akhtar
2022-04-27 15:58 ` [PATCH 08/10] ARM: dts: exynos: " Krzysztof Kozlowski
2022-04-27 15:58   ` Krzysztof Kozlowski
2022-04-27 16:44   ` Alim Akhtar
2022-04-27 16:44     ` Alim Akhtar
2022-04-28  9:50   ` Marek Szyprowski
2022-04-28  9:50     ` Marek Szyprowski
2022-04-28  9:54     ` Krzysztof Kozlowski
2022-04-28  9:54       ` Krzysztof Kozlowski
2022-04-28  9:57       ` Marek Szyprowski
2022-04-28  9:57         ` Marek Szyprowski
2022-04-28 10:00         ` Krzysztof Kozlowski
2022-04-28 10:00           ` Krzysztof Kozlowski
2022-04-28 10:05           ` Marek Szyprowski [this message]
2022-04-28 10:05             ` Marek Szyprowski
2022-04-28 10:09             ` Krzysztof Kozlowski
2022-04-28 10:09               ` Krzysztof Kozlowski
2022-04-28 13:33               ` Rob Herring
2022-04-28 13:33                 ` Rob Herring
2022-04-28  9:55     ` Alim Akhtar
2022-04-28  9:55       ` Alim Akhtar
2022-04-27 15:58 ` [PATCH 09/10] arm64: " Krzysztof Kozlowski
2022-04-27 15:58   ` Krzysztof Kozlowski
2022-04-27 16:46   ` Alim Akhtar
2022-04-27 16:46     ` Alim Akhtar
2022-04-27 15:58 ` [PATCH 10/10] arm64: dts: fsd: " Krzysztof Kozlowski
2022-04-27 15:58   ` Krzysztof Kozlowski
2022-04-27 16:49   ` Alim Akhtar
2022-04-27 16:49     ` Alim Akhtar

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