linux-kernel - Re: [PATCH v2 tty-next] 8250: microchip: pci1xxxx: Add PCIe Hot reset disable support for Rev C0 and later devices

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Message-ID: <fe7b07d35ded71e71ab892909284727a57604bdb.camel@microchip.com>
Date: Fri, 25 Apr 2025 13:39:46 +0000
From: <Rengarajan.S@...rochip.com>
To: <gregkh@...uxfoundation.org>
CC: <jirislaby@...nel.org>, <linux-serial@...r.kernel.org>,
	<UNGLinuxDriver@...rochip.com>, <Kumaravel.Thiagarajan@...rochip.com>,
	<linux-kernel@...r.kernel.org>, <Tharunkumar.Pasumarthi@...rochip.com>
Subject: Re: [PATCH v2 tty-next] 8250: microchip: pci1xxxx: Add PCIe Hot reset
 disable support for Rev C0 and later devices

Hi Greg,

Thanks for reviewing the patch.

On Fri, 2025-04-25 at 13:45 +0200, Greg KH wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you
> know the content is safe
> 
> On Thu, Apr 24, 2025 at 09:29:13AM +0530, Rengarajan S wrote:
> > Systems that issue PCIe hot reset requests during a suspend/resume
> > cycle cause PCI1XXXX device revisions prior to C0 to get its UART
> > configuration registers reset to hardware default values. This
> > results
> > in device inaccessibility and data transfer failures. Starting with
> > Revision C0, support was added in the device hardware (via the Hot
> > Reset Disable Bit) to allow resetting only the PCIe interface and
> > its
> > associated logic, but preserving the UART configuration during a
> > hot
> > reset. This patch enables the hot reset disable feature during
> > suspend/
> > resume for C0 and later revisions of the device.
> > 
> > v2
> > Retained the original writel and simplified the hot reset condition
> > v1
> > Initial Commit.
> > 
> > Signed-off-by: Rengarajan S <rengarajan.s@...rochip.com>
> > ---
> >  drivers/tty/serial/8250/8250_pci1xxxx.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> > 
> > diff --git a/drivers/tty/serial/8250/8250_pci1xxxx.c
> > b/drivers/tty/serial/8250/8250_pci1xxxx.c
> > index e9c51d4e447d..61849312393b 100644
> > --- a/drivers/tty/serial/8250/8250_pci1xxxx.c
> > +++ b/drivers/tty/serial/8250/8250_pci1xxxx.c
> > @@ -115,6 +115,7 @@
> > 
> >  #define UART_RESET_REG                               0x94
> >  #define UART_RESET_D3_RESET_DISABLE          BIT(16)
> > +#define UART_RESET_HOT_RESET_DISABLE            BIT(17)
> 
> You forgot to use tabs here :(

Apologies, will update in the next revision.

>