From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Rengarajan.S@microchip.com
Cc: Kumaravel.Thiagarajan@microchip.com,
jiaqing.zhao@linux.intel.com, gregkh@linuxfoundation.org,
ilpo.jarvinen@linux.intel.com, john.ogness@linutronix.de,
tony@atomide.com, linux-kernel@vger.kernel.org,
Tharunkumar.Pasumarthi@microchip.com, jirislaby@kernel.org,
f.fainelli@gmail.com, tglx@linutronix.de,
UNGLinuxDriver@microchip.com, linux-serial@vger.kernel.org
Subject: Re: [PATCH v1 tty] 8250: microchip: Add 4 Mbps support in PCI1XXXX UART
Date: Thu, 1 Feb 2024 13:52:07 +0200 [thread overview]
Message-ID: <ZbuF53TlbnD09rZA@smile.fi.intel.com> (raw)
In-Reply-To: <8406d8866968950b9bb2f2c01aaa92e3107a7a00.camel@microchip.com>
On Tue, Jan 30, 2024 at 10:52:41AM +0000, Rengarajan.S@microchip.com wrote:
> On Sun, 2024-01-28 at 17:27 +0200, Andy Shevchenko wrote:
> > On Thu, Jan 25, 2024 at 03:36:19PM +0530, Rengarajan S wrote:
...
> > > + /*
> > > + * Microchip PCI1XXXX UART supports maximum baud rate up to 4
> > > Mbps
> > > + */
> > > + if (up->port.type == PORT_MCHP16550A)
> > > + max = 4000000;
> >
> > No. Please refactor the way the 8250_port won't be modified.
> >
> > Also you have a define for this constant, use it.
>
> The current UART clk in MCHP Ports in pci1xxxx.c is set to 62.5 MHz in
> order to support fractional baud rates which enables generation of
> acceptable baud rate and lower error percentage from any available
> frequency. With 62.5 MHz the maximum supported baud rate supported as
> per serial_8250_get_baud_rate is 3.9 Mbps. In order to extend the
> support to 4 Mbps we had hardcoded the max value to 4 Mbps. Since, baud
> rate is calculated here we needed to make these changes in 8250_port
> and could not find a way to handle as part 8250_pci1xxxx. Can you let
> us know any alternatives to address this upper(max) limit?
Update port->uartclk accordingly in your driver, see how other 8250_* drivers
do that (e.g., 8250_mid).
So, it will no go with hack in the 8250_port.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2024-02-01 11:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-25 10:06 [PATCH v1 tty] 8250: microchip: Add 4 Mbps support in PCI1XXXX UART Rengarajan S
2024-01-28 15:27 ` Andy Shevchenko
2024-01-28 15:28 ` Andy Shevchenko
2024-01-30 10:52 ` Rengarajan.S
2024-02-01 11:52 ` Andy Shevchenko [this message]
2024-02-08 2:53 ` Rengarajan.S
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