Re: [PATCH LINUX v3 00/10] tty: xuartps: Fix lock ups

From: Peter Hurley
Date: Sat Dec 05 2015 - 12:49:15 EST


On 11/21/2015 09:59 PM, Soren Brinkmann wrote:
> Hi,
>
> here is v3 of this series. It's largely the same as before, but I
> adjusted 'tty: xuartps: Don't consider circular buffer when enabling
> transmitter' according to Peter's suggestions.

In reviewing this series, I thought the _OFFSET suffix for every register
address to be excessive. I would refactor all that out; IOW,

- isrstatus = readl(port->membase + CDNS_UART_ISR_OFFSET);
+ isrstatus = readl(port->membase + CDNS_UART_ISR);


> I also spent some time trying to get Peter's test for flow control and
> xchar running. The xchar thing fails and will need some more work, but I
> think in general it should be possible to get it to work.
> The flow control test passes:
>
> root@Xilinx-ZC1751-DC1:~# ./flow /dev/ttyPS0
> Test flow control on /dev/ttyPS0
> begin test1
> patterns sent: 223 recvd: 208
> read distribution: 1 = 0
> 2+ = 0
> 4+ = 0
> 8+ = 0
> 16+ = 0
> 32+ = 643
> 64+ = 0
> 128+ = 0
> 256+ = 0
> 512+ = 0
> PASSED

This distribution looks like this exactly because the xchar test is
failing. IOW, this driver isn't performing soft flow control (^S,^Q)
like it should.

Regards,
Peter Hurley

> root@Xilinx-ZC1751-DC1:~# ./flow /dev/ttyPS1
> Test flow control on /dev/ttyPS1
> begin test1
> patterns sent: 223 recvd: 208
> read distribution: 1 = 0
> 2+ = 0
> 4+ = 0
> 8+ = 0
> 16+ = 0
> 32+ = 643
> 64+ = 0
> 128+ = 0
> 256+ = 0
> 512+ = 0
> PASSED
>
> SÃren
>
> SÃren Brinkmann (10):
> tty: xuartps: Beautify read-modify writes
> tty: xuartps: Use spinlock to serialize HW access
> tty: xuartps: Don't consider circular buffer when enabling transmitter
> tty: xuartps: Clear interrupt status register in shutdown
> tty: xuartps: Improve startup function
> tty: xuartps: Keep lock for whole ISR
> tty: xuartps: Acquire port lock for shutdown
> tty: xuartps: Move RX path into helper function
> tty: xuartps: Only handle RX IRQs when RX is enabled
> tty: xuartps: Cleanup: Reformat if-else
>
> drivers/tty/serial/xilinx_uartps.c | 246 +++++++++++++++++++++----------------
> 1 file changed, 137 insertions(+), 109 deletions(-)
>

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