Re: [PATCH v4 10/11] arm64: dts: mt7986: add Bananapi R3

From: Frank Wunderlich <frank-w@public-files.de>
To: Daniel Golle <daniel@makrotopia.org>
Cc: linux-mediatek@lists.infradead.org, devicetree@vger.kernel.org,
	Ryder Lee <ryder.lee@mediatek.com>,
	Bo Jiao <Bo.Jiao@mediatek.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-phy@lists.infradead.org,
	Kishon Vijay Abraham I <kishon@ti.com>,
	Jianjun Wang <jianjun.wang@mediatek.com>,
	Chunfeng Yun <chunfeng.yun@mediatek.com>,
	Vinod Koul <vkoul@kernel.org>, Rob Herring <robh+dt@kernel.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	linux-pci@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
	Paolo Abeni <pabeni@redhat.com>,
	Lorenzo Bianconi <lorenzo@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 10/11] arm64: dts: mt7986: add Bananapi R3
Date: Wed, 16 Nov 2022 10:06:29 +0100	[thread overview]
Message-ID: <46481C3B-3B46-440F-B923-02934E0445F1@public-files.de> (raw)
In-Reply-To: <Y3QMMKGc6uNFyfWb@makrotopia.org>

Am 15. November 2022 23:01:20 MEZ schrieb Daniel Golle <daniel@makrotopia.org>:

>The device can boot from all 4 storage options. Both, SPI and MMC, can
>be switched using hardware switches on the board, see
>https://wiki.banana-pi.org/Banana_Pi_BPI-R3#Jumper_setting
>
>So why do the SPI-NAND vs. SPI-NOR switching with device tree overlays
>and the SD card vs. eMMC switching with dtsi + 2x dts? To me this looks
>inconsitent. Use either one or the other method.

Hi Daniel

It is still in discussion,if mainline-kernel will support devicetree-overlays [1].

I used this way to have at least 1 dtb without overlay for booting kernel from sdcard which is the only external storage.

If mainline kernel rejects dto, we have no "broken" dtb which only allows bootup with initrd. We can boot this board from sdcard with mainline code only (maybe some users don't need emmc,nand,nor).

As you cannot delete (sd specific) properties in overlays,i added emmc variant. And now we can use overlays to support spi devices,which are not needed for first bootup,but to access emmc.

Imho my current sd/emmc dts can be easily converted to dtso and base dtsi needs only to be renamed. But all only if the big question below is answered.

[1] https://patchwork.kernel.org/project/linux-mediatek/patch/20221106085034.12582-12-linux@fw-web.de/#25085681

regards Frank