From: Palmer Dabbelt <palmer@sifive.com>
To: Paul Walmsley <paul.walmsley@sifive.com>
Cc: linux-riscv@lists.infradead.org,
Alistair Francis <Alistair.Francis@wdc.com>,
linux-kernel@vger.kernel.org,
Paul Walmsley <paul.walmsley@sifive.com>
Subject: Re: [PATCH] RISC-V: defconfig: Enable Generic PCIE by default
Date: Wed, 26 Dec 2018 08:52:48 -0800 (PST) [thread overview]
Message-ID: <mhng-ceba7c1a-7334-4869-a7d4-2326b59f82b5@palmer-si-x1c4> (raw)
In-Reply-To: <alpine.DEB.2.21.9999.1812211124180.777@viisi.sifive.com>
On Fri, 21 Dec 2018 11:27:39 PST (-0800), Paul Walmsley wrote:
>
> On Fri, 21 Dec 2018, Alistair Francis wrote:
>
>> When the MicroSemi driver does eventually go upstream this will
>> probably have to be discussed though as either the config or device
>> tree will need to be edited to ensure only one PCIe device is present.
>
> The right way to do that is to have two separate DT files: one for the
> HiFive-U board alone; the other for the HiFive-U plus the expansion board
> combo. There shouldn't be any problems with keeping both drivers enabled
> in the defconfig.
We actually need at least three:
* One for the HiFive Unleashed
* One for the HiFive Unleashed, when attached to the Micro Semi expansion
board.
* One for the HiFive Unleashed, when attached to a VC707.
We may end up needing additional device trees for the newer Xilinx boards,
depending on if it's possible to probe for that 32-bit DMA limit on the VC707
or not. Then, of course, we'll need an image-specific device tree whenever we
put an accelerator on the FPGA.
Ideally we'd have a discoverable bus, but that's going to be a bit of a way
out. For now we'll have to get by with different device trees, but that should
get significantly easier when we get a proper bootloader working.
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prev parent reply other threads:[~2018-12-26 16:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-21 19:06 [PATCH] RISC-V: defconfig: Enable Generic PCIE by default Alistair Francis
2018-12-21 19:13 ` Paul Walmsley
2018-12-21 19:22 ` Alistair Francis
2018-12-21 19:27 ` Paul Walmsley
2018-12-21 22:11 ` Alistair Francis
2018-12-21 22:34 ` Paul Walmsley
2018-12-21 23:03 ` Alistair Francis
2018-12-26 16:52 ` Palmer Dabbelt [this message]
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