RE: [EXT] Re: [PATCH 02/11] dts: mvebu: Update A8K AP806 SDHCI settings

From: Kostya Porotchkin <kostap@marvell.com>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Baruch Siach <baruch@tkos.co.il>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"andrew@lunn.ch" <andrew@lunn.ch>,
	"jaz@semihalf.com" <jaz@semihalf.com>,
	"gregory.clement@bootlin.com" <gregory.clement@bootlin.com>,
	Nadav Haklai <nadavh@marvell.com>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	Stefan Chulski <stefanc@marvell.com>,
	"mw@semihalf.com" <mw@semihalf.com>,
	Ben Peled <bpeled@marvell.com>,
	"sebastian.hesselbarth@gmail.com"
	<sebastian.hesselbarth@gmail.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Subject: RE: [EXT] Re: [PATCH 02/11] dts: mvebu: Update A8K AP806 SDHCI settings
Date: Wed, 3 Feb 2021 16:57:09 +0000	[thread overview]
Message-ID: <DM5PR18MB14525D61BC500B0026F30D07CAB49@DM5PR18MB1452.namprd18.prod.outlook.com> (raw)
In-Reply-To: <20210203161137.GS1463@shell.armlinux.org.uk>

Hello, Russell,
I agree that this patch needs rework.
I will definitely do it and issue a new version.

> On Wed, Feb 03, 2021 at 02:50:45PM +0000, Kostya Porotchkin wrote:
> > [KP] So for older systems this "slow mode" parameter could be set on the
> board level.
> > When it is set in ap80x,dtsi file it downgrades all systems to HS-SDR52, even
> if they support HS400 on AP side.
> > MacchiatoBIN AP eMMC is connected to 3.3v regulator and has "no-1-8-v"
> flag set, so it should remain in low speed anyway.
> 
> Your reasoning does not make sense.
> 
> The ap80x.dtsi file does not specify "marvell,xenon-phy-slow-mode".
> It is not specified at this level. It is already specified at board level.
[KP] it does. In current armada-ap80x.dtsi File this specification is on row 260:
			ap_sdhci0: sdhci@6e0000 {
				compatible = "marvell,armada-ap806-sdhci";
				reg = <0x6e0000 0x300>;
				interrupts = <GIC_SPI 16 IRQ_TYPE_LEVEL_HIGH>;
				clock-names = "core";
				clocks = <&ap_clk 4>;
				dma-coherent;
				marvell,xenon-phy-slow-mode;
				status = "disabled";
			};
So I would like to remove this row.

> Given that Macchiatobin will still use slow mode, why remove the
> marvell,xenon-phy-slow-mode property from this file?
[KP] Agree, I will keep this property in Macchiatobin DTS file.

> 
> Also, if you're upgrading ap80x.dtsi to use a bus-width of 8, why keep the bus-
> width specifier of 8 in the board files?
[KP] The bus width is updated in A8040 DB DTS. This board utilizes 8-bit interface.
The armada-ap80x.dtsi file does not specifies the bus width since it is board-specific.

> 
> This patch just doesn't make sense, and your responses to our points seem to
> add to the confusion.
[KP] I am sorry about it. Hope my last response clarifies it.

Kosta
> 
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