Re: [PATCH] PCI: enable extended tags support for PCIe endpoints

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

 



On 11/11/2016 3:58 PM, Bjorn Helgaas wrote:
>> I should have checked the capability here before trying to enable it. 
>> > I'll post a follow up patch on this. 
>> > 
>> > Is there any other feedback?
> If this were completely safe to enable for every device that supported
> it, why would there be an enable bit in Device Control?

reading from the ECN here.

https://pcisig.com/sites/default/files/specification_documents/ECN_Extended_Tag_Enable_Default_05Sept2008_final.pdf

The initial value is implementation specific and functions are allowed
to set it to 1 by default.

> 
> I don't know anything about extended tags, but it worries me a little
> when there's a "go-fast" switch and no explanation about when and why
> we might need to go slo

Based on my observation, extended tags increase the number of reads that
can be queued up back to back downstream. Otherwise, the requests will not
make progress until 1 tag out of 32 gets available.

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [Linux for Sparc]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux