Re: [PATCH 2/6] scsi: hisi_sas: workaround a SoC SATA IO processing bug

From: Johannes Thumshirn
Date: Mon Apr 10 2017 - 10:07:15 EST


On Mon, Apr 10, 2017 at 09:21:57PM +0800, John Garry wrote:
> From: Xiaofei Tan <tanxiaofei@xxxxxxxxxx>
>
> This patch provides a workaround a SoC bug where SATA IPTTs for
> different devices may conflict.
>
> The workaround solution requests the following:
> 1. SATA device id must be even and not equal to SAS IPTT.
> 2. SATA device can not share the same IPTT with other SAS or
> SATA device.
>
> Besides we shall consider IPTT value 0 is reserved for another SoC
> bug (STP device open link at firstly after SAS controller reset).
>
> To sum up, the solution is:
> Each SATA device uses independent and continuous 32 even IPTT from
> 64 to 4094, then v2 hw can only support 63 SATA devices.
> All SAS device(SSP/SMP devices) share odd IPTT value from 1 to
> 4095.
>
> Signed-off-by: Xiaofei Tan <tanxiaofei@xxxxxxxxxx>
> Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
> ---

Reviewed-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
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