Re: [PATCH v7 1/2] serial: sc16is7xx

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, 25 Apr 2014, Jon Ringle wrote:

> On Fri, Apr 25, 2014 at 9:44 AM, Charles Coldwell <coldwell@xxxxxxxxx> wrote:
> > On Fri, 25 Apr 2014, Charles Coldwell wrote:
> >
> >> On Thu, 24 Apr 2014, jon@xxxxxxxxxx wrote:
> >>
> >> > diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
> >>
> >> Isn't this a lot of duplication?
> >
> > Actually, the whole thing seems like duplication to me.
> 
> The fact that we need to reach over the SPI/I2C bus makes a big
> difference in the way access is handled.
> 
> To achieve acceptable throughput, it is necessary to use threaded irq
> and also bulk i2c transfers for RX and TX using
> regmap_raw_{read,write}() to optimize the use of the i2c bus.

Fair enough, but the 8250 framework does allow you to insert your own
irq service routine. "serial8250_default_handle_irq" is the default
(unsurprisingly), but if the uart_port has a non-NULL "handle_irq"
method it will be faithfully copied into the uart_8250_port
"handle_irq" method in 8250_core.c:early_serial_setup.

> This is not a good fit for 8250.

If that's really true, then I would say it argues in favor of a
revision of the 8250 code.  Certainly, this is not the last time that
a 16550-compatible UART will appear on a non-PCI, non-ISA bus.

-- 
Charles M. Coldwell, W1CMC
"Turn on, log in, tune out"
Somerville, Massachusetts, New England (FN42kj)

GPG ID:  852E052F
GPG FPR: 77E5 2B51 4907 F08A 7E92  DE80 AFA9 9A8F 852E 052F
--
To unsubscribe from this list: send the line "unsubscribe linux-serial" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Linux PPP]     [Linux FS]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Linmodem]     [Device Mapper]     [Linux Kernel for ARM]

  Powered by Linux