From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Palmer Dabbelt <palmer@dabbelt.com>
Cc: apatel@ventanamicro.com, Greg KH <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org, andrei.warkentin@intel.com,
linux-serial@vger.kernel.org, linux-riscv@lists.infradead.org,
dfustini@tenstorrent.com, jirislaby@kernel.org,
ajones@ventanamicro.com
Subject: Re: [PATCH] serial: 8250_platform: Enable generic 16550A platform devices
Date: Tue, 17 Sep 2024 16:58:35 +0300 [thread overview]
Message-ID: <ZumLC9I1Jf82Y8T-@smile.fi.intel.com> (raw)
In-Reply-To: <mhng-d52ac6ff-2221-4613-9fce-f73467495389@palmer-ri-x1c9>
On Tue, Sep 17, 2024 at 06:10:25AM -0700, Palmer Dabbelt wrote:
> On Mon, 29 Jul 2024 22:12:18 PDT (-0700), Sunil V L wrote:
> > Currently, 8250_platform driver is used only for devices with fixed
> > serial ports (plat_serial8250_port). Extend this driver for any generic
> > 16550A platform devices which can be probed using standard hardware
> > discovery mechanisms like ACPI.
> >
> > This is required in particular for RISC-V which has non-PNP generic
> > 16550A compatible UART that needs to be enumerated as ACPI platform
> > device.
> It seems a bit awkward that we need something RISC-V specific here. I
> guess the idea is that we don't want to depend on PNP because we'd end
> up with a bunch of PCI dependencies as well? That seems like kind of an
> odd way to do things, but I'm frequently suprised by ACPI stuff so
We have the same for HSUART on Intel (see 8250_dw.c). The ACPI devices use
different approach than PNP. PNP has the exact requirements for compatibility
with the legacy UARTs (to some extend). It puts some limitations. I believe
having specifics for RISC-V is fine. But I haven't checked the real IP used
in the SoC. If it's one that we have the existing driver for (like again
mentioned 8250_dw.c), then it should be added there.
TL;DR: so, what is the IP is in hardware for UART? Custom?
--
With Best Regards,
Andy Shevchenko
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prev parent reply other threads:[~2024-09-17 13:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-30 5:12 [PATCH] serial: 8250_platform: Enable generic 16550A platform devices Sunil V L
2024-09-17 13:10 ` Palmer Dabbelt
2024-09-17 13:58 ` Andy Shevchenko [this message]
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