Re: [Xen-devel] [PATCH] serial: Skip over PCIe device which have no quirks (fix AMT regression).

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Mar 05, 2014 at 02:45:39PM -0500, Konrad Rzeszutek Wilk wrote:
> The "ns16550: Add support for UART present in Broadcom TruManage
> capable NetXtreme chips" implies that only devices that are have
> an MMIO BAR and are in the quirks table should be processed.
> 
> Even the comment at the end says so:
> 
>  If we have an io_base, then we succeeded in the lookup
> 
> But the code was checking for the !io_base - which is to say if
> the io_base was NULL then we would skip scanning.
> 
> This means that if we have an communication device followed by
> a serial AMT device we would pick the communication device instead
> of the MMIO.
> 
> See:
> 00:16.0 Communication controller: Intel Corporation Cougar Point HECI 
> Controller #1 (rev 04)
>         Subsystem: Intel Corporation Device 2008
>         Flags: bus master, fast devsel, latency 0, IRQ 11
>         Memory at fb12a000 (64-bit, non-prefetchable) [size=16]
> 00:16.3 Serial controller: Intel Corporation Cougar Point KT Controller (rev 
> 04) (prog-if 02 [16550])
>         Subsystem: Intel Corporation Device 2008
>         Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 17
>         I/O ports at f0e0 [size=8]
>         Memory at fb129000 (32-bit, non-prefetchable) [size=4K]
> 
> pci 0000:00:16.0: [8086:1c3a] type 00 class 0x078000
> pci 0000:00:16.3: [8086:1c3d] type 00 class 0x070002
> 
> This patch fixes it and allows us to use AMT again.

Lets ignore this patch. It would break the PCIe card with MMIO as
now we don't setup the rest of the uart configuration for
cards that are found to be on the quirk list.  

> 
> CC: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@xxxxxxx>
> CC: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>
> CC: Thomas Lendacky <Thomas.Lendacky@xxxxxxx>
> CC: Jan Beulich <jbeulich@xxxxxxxx>
> CC: Keir Fraser <keir@xxxxxxx>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>  xen/drivers/char/ns16550.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c
> index 53e49a1..8a908bd 100644
> --- a/xen/drivers/char/ns16550.c
> +++ b/xen/drivers/char/ns16550.c
> @@ -707,7 +707,7 @@ pci_uart_config (struct ns16550 *uart, int skip_amt, int 
> bar_idx)
>                      }
>  
>                      /* If we have an io_base, then we succeeded in the 
> lookup */
> -                    if ( !uart->io_base )
> +                    if ( uart->io_base )
>                          continue;
>                  }
>                  /* IO based */
> -- 
> 1.7.7.6
> 

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