linux-kernel - Re: [v3] PCI: cadence: Fix sending message with data or without data

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Message-ID: <20250214155725.jpkd4vtcycav4yrc@thinkpad>
Date: Fri, 14 Feb 2025 21:27:25 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Hans Zhang <18255117159@....com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	lpieralisi@...nel.org, kw@...ux.com, robh@...nel.org,
	bhelgaas@...gle.com, bwawrzyn@...co.com, cassel@...nel.org,
	wojciech.jasko-EXT@...tinental-corporation.com, a-verma1@...com,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	rockswang7@...il.com
Subject: Re: [v3] PCI: cadence: Fix sending message with data or without data

On Fri, Feb 14, 2025 at 11:48:16PM +0800, Hans Zhang wrote:
> 
> 
> On 2025/2/14 23:31, Manivannan Sadhasivam wrote:
> > On Fri, Feb 14, 2025 at 10:28:11PM +0800, Hans Zhang wrote:
> > > Sorry Mani, I shouldn't have spread this SOC bug. This is a bug in RTL
> > > design, the WSTRB signal of AXI bus is not connected correctly, so the first
> > > generation SOC cannot send message, because we mainly use RC mode, and we
> > > cannot send PME_Turn_OFF, that is, our SOC does not support L2. I have no
> > > choice about this, I entered the company relatively late, and our SOC has
> > > already TO.
> > 
> > Ok. Just to clear my head, this patch is needed irrespective of the hw issue,
> > right? And with or without this patch, first revision hw cannot send any MSG
> > TLPs?
> 
> Yes, that was a problem with our own SOC design, the Cadence RTL bug.	
> 
> > If so, it is fine. But is there a way we could detect those first generation IPs
> > and flag it to users about broken MSG TLP support? Atleast, that would make the
> > users aware of broken hw.
> 
> I don't know how to do it, but here are the questions that were actually
> tested.
> 

Not related to this patch, but please check if it is possible to detect those
controllers.

> > > 
> > > This patch is to solve the Cadence common code bug, and does not conform to
> > > Cadence documentation.
> > 
> > you mean 'does'?
> > 
> 
> What I mean is that common code bit16=1 is to send a message without data,
> while Cadence's development document says that bit16=0 is to send a message
> without data. This is not consistent with the documentation description, and
> the final verification results, the development documentation described is
> correct.
> 

Ok, makes sense now.

- Mani

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