linux-kernel - Re: [PATCH v1 7/9] riscv: dts: add initial SpacemiT K1 SoC device tree

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Date: Tue, 18 Jun 2024 01:01:32 +0800
From: Yangyu Chen <cyy@...self.name>
To: Jisheng Zhang <jszhang@...nel.org>
Cc: Conor Dooley <conor.dooley@...rochip.com>,
 linux-riscv@...ts.infradead.org,
 Conor Dooley <conor+dt@...nel.org>,
 Palmer Dabbelt <palmer@...belt.com>,
 Paul Walmsley <paul.walmsley@...ive.com>,
 Samuel Holland <samuel.holland@...ive.com>,
 Anup Patel <anup.patel@....com>,
 Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>,
 devicetree@...r.kernel.org,
 Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 7/9] riscv: dts: add initial SpacemiT K1 SoC device
 tree



> On Jun 17, 2024, at 21:31, Jisheng Zhang <jszhang@...nel.org> wrote:
> 
> On Mon, Jun 17, 2024 at 02:29:46PM +0100, Conor Dooley wrote:
>> On Mon, Jun 17, 2024 at 08:49:57PM +0800, Jisheng Zhang wrote:
>>> On Mon, Jun 17, 2024 at 01:20:52AM +0800, Yangyu Chen wrote:
>>>> Banana Pi BPI-F3 motherboard is powered by SpacemiT K1[1].
>>>> 
>>>> Key features:
>>>> - 4 cores per cluster, 2 clusters on chip
>>>> - UART IP is Intel XScale UART
>>>> 
>>>> Some key considerations:
>>>> - ISA string is inferred from vendor documentation[2]
>>>> - Cluster topology is inferred from datasheet[1] and L2 in vendor dts[3]
>>>> - No coherent DMA on this board
>>>>    Inferred by taking vendor ethernet and MMC drivers to the mainline
>>>>    kernel. Without dma-noncoherent in soc node, the driver fails.
>>>> - No cache nodes now
>>>>    The parameters from vendor dts are likely to be wrong. It has 512
>>>>    sets for a 32KiB L1 Cache. In this case, each set is 64B in size.
>>>>    When the size of the cache line is 64B, it is a directly mapped
>>>>    cache rather than a set-associative cache, the latter is commonly
>>>>    used. Thus, I didn't use the parameters from vendor dts.
>>>> 
>>>> Currently only support booting into console with only uart, other
>>>> features will be added soon later.
>>> 
>>> Hi Yangyu,
>>> 
>>> Per recent practice of cv1800b and th1520 upstream, I think a complete
>>> initial support would include pinctrl, clk and reset, I have received
>>> the complains from the community. So can you please bring the pinctrl
>>> clk  and reset at the same time?
>> 
>> What sort of complaints have you got? That the support is too minimal to
>> be useful?
> 
> For example https://lore.kernel.org/linux-riscv/95c20c6c-66cd-4f87-920b-5da766317e19@sifive.com/
> 
> Now, I think it's better to "model the clocks/resets/other dependencies"
> in the initial support. So lacking of pinctrl, clk and reset doesn't
> fully describe the hardware.

Sound like a good idea. In this case, we don't need to change the
dts repeatedly after a new soc driver is supported.