linux-kernel - Re: [PATCH v2 0/2] serial: 8250_dw: fall back to poll if there's no interrupt

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Message-ID: <ZM9y93rVVnIIQzzP@xhacker>
Date:   Sun, 6 Aug 2023 18:16:23 +0800
From:   Jisheng Zhang <jszhang@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Jiri Slaby <jirislaby@...nel.org>,
        linux-serial@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/2] serial: 8250_dw: fall back to poll if there's no
 interrupt

On Sun, Aug 06, 2023 at 12:20:11PM +0200, Greg Kroah-Hartman wrote:
> On Sun, Aug 06, 2023 at 05:20:54PM +0800, Jisheng Zhang wrote:
> > When there's no irq(this can be due to various reasons, for example,
> > no irq from HW support, or we just want to use poll solution, and so
> > on), falling back to poll is still better than no support at all.
> 
> Ouch, really?  Why not just fix the hardware instead?
> 

Hi Greg,

The HW may be designed as that to save interrupt lines if the uart
is dedicated to debug purpose. I also see similar support in other
uart drivers, for example liteuart.c, altera_uart.c, altera_jtaguart.c
8250_ioc3.c and so on.

Thanks