RE: [EXT] Re: [PATCH v3 2/2] serial: 8250_dw: add Ambarella CV75 quirks

Hi Andy,

Thanks for the review. Agreed the commit message was too brief.

This is not a silicon erratum. The Ambarella UART is not Synopsys
DesignWare IP; it is an Ambarella 8250-compatible UART. We still use
the snps-dw-apb-uart binding / 8250_dw because the programming model
matches closely enough, with two quirks (ETOI IER bit and
SKIP_SET_RATE). I will expand the commit message and rewrite the
comment to explain why in the next revision.

Best regards!
Long Zhao

Ambarella Shanghai Co., Ltd
-----Original Message-----
From: Andy Shevchenko <[email protected]> 
Sent: Friday, August 14, 2026 16:56
To: Long Zhao <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>; Jiri Slaby <[email protected]>; Rob Herring <[email protected]>; Krzysztof Kozlowski <[email protected]>; Conor Dooley <[email protected]>; Linus Walleij <[email protected]>; Ilpo Järvinen <[email protected]>; [email protected]; [email protected]; [email protected]
Subject: [EXT] Re: [PATCH v3 2/2] serial: 8250_dw: add Ambarella CV75 quirks

On Thu, Aug 13, 2026 at 06:35:13PM +0800, Long Zhao via B4 Relay wrote:

> Add CV75 platform data with an ETOI IER mask and skip-set-rate so the 
> DesignWare 8250 driver can drive the Ambarella UART for console use.

...

> +	/* Keep variant-specific bits in the shadow across subsequent 
> +updates. */

This says what code is doing. Instead it must say "why?" the code is doing this.

> +	up->ier |= d->pdata->ier_mask;
> +	serial_port_out(p, UART_IER, up->ier);

...

In case there is an HW bug, where can we get the errata, please? (For a bare minimum add a reference to the Errata document you give to the customers.)

--
With Best Regards,
Andy Shevchenko



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