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From:   Chunyan Zhang <zhang.lyra@gmail.com>
Date:   Wed, 9 Aug 2023 14:23:02 +0800
Message-ID: <CAAfSe-utHwSZnX4SqhYsvzF5+p5A4DfYvFwZGOMjkEsu_8qsLw@mail.gmail.com>
Subject: Re: [PATCH] serial: sprd: Support 12 uart ports
To:     wenhua lin <wenhua.lin1994@gmail.com>
Cc:     Baolin Wang <baolin.wang@linux.alibaba.com>,
        Wenhua Lin <Wenhua.Lin@unisoc.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Orson Zhai <orsonzhai@gmail.com>, linux-serial@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Xiongpeng Wu <xiongpeng.wu@unisoc.com>
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On Wed, 9 Aug 2023 at 13:52, wenhua lin <wenhua.lin1994@gmail.com> wrote:
>
> The change of the max ports is to adapt to an new
> SPRD serial hardware,also is backward-compatibility with old hardware.

This change seems not backward-compatible if the serial devices on
some old Unisoc SoCs can support 8 ports only.

BTW, please do not top-post your reply.

Thanks,
Chunyan

>
> Baolin Wang <baolin.wang@linux.alibaba.com> =E4=BA=8E2023=E5=B9=B48=E6=9C=
=887=E6=97=A5=E5=91=A8=E4=B8=80 16:41=E5=86=99=E9=81=93=EF=BC=9A
> >
> >
> >
> > On 8/7/2023 4:07 PM, Wenhua Lin wrote:
> > > From: Wenhua Lin <wenhua.lin@unisoc.com>
> > >
> > > Support 12 uart ports, which can solve the problem
> > > of insufficient uart ports.
> >
> > This sounds incorrect to me.
> > If this is a software bug, please add a Fixes tag to backport for stabl=
e
> > kernels. If the change of the max ports is only avaliable on the new
> > SPRD serial hardware, you should ensure the change is
> > backward-compatibility with old hardware.
> >
> > > Signed-off-by: Wenhua Lin <wenhua.lin@unisoc.com>
> > > ---
> > >   drivers/tty/serial/sprd_serial.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sp=
rd_serial.c
> > > index b58f51296ace..2774df490899 100644
> > > --- a/drivers/tty/serial/sprd_serial.c
> > > +++ b/drivers/tty/serial/sprd_serial.c
> > > @@ -22,7 +22,7 @@
> > >   #include <linux/tty_flip.h>
> > >
> > >   /* device name */
> > > -#define UART_NR_MAX          8
> > > +#define UART_NR_MAX          12
> > >   #define SPRD_TTY_NAME               "ttyS"
> > >   #define SPRD_FIFO_SIZE              128
> > >   #define SPRD_DEF_RATE               26000000