Re: [PATCH v2 2/2] serial: 8250: Add new 8250-core based Broadcom STB driver

From: Greg Kroah-Hartman
Date: Mon Jan 18 2021 - 12:48:33 EST

On Fri, Jan 15, 2021 at 04:15:43PM -0500, Al Cooper wrote:
> Add a UART driver for the new Broadcom 8250 based STB UART. The new
> UART is backward compatible with the standard 8250, but has some
> additional features. The new features include a high accuracy baud
> rate clock system and DMA support.
> The driver will use the new optional BAUD MUX clock to select the best
> one of the four master clocks (81MHz, 108MHz, 64MHz and 48MHz) to feed
> the baud rate selection logic for any requested baud rate. This allows
> for more accurate BAUD rates when high speed baud rates are selected.
> The driver will use the new UART DMA hardware if the UART DMA registers
> are specified in Device Tree "reg" property. The DMA functionality can
> be disabled on kernel boot with the argument:
> "8250_bcm7271.disable_dma=Y".

Shouldn't that be on a per-device basis, and not a per-driver basis?

And why would you want to disable this, if you have support for this in
the DT? Why not just rely on the DT setting?


greg k-h