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

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Message-ID: <20250214132115.fpiqq65tqtowl2wa@thinkpad>
Date: Fri, 14 Feb 2025 18:51:15 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Hans Zhang <18255117159@....com>
Cc: 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 04:23:33PM +0800, Hans Zhang wrote:
> 
> 
> On 2025/2/14 15:30, Manivannan Sadhasivam wrote:
> > On Fri, Feb 07, 2025 at 06:39:23PM +0800, Hans Zhang wrote:
> > > View from cdns document cdn_pcie_gen4_hpa_axi_ips_ug_v1.04.pdf.
> > > In section 9.1.7.1 AXI Subordinate to PCIe Address Translation
> > > Registers below:
> > > 
> > > axi_s_awaddr bits 16 is 1 for MSG with data and 0 for MSG without data.
> > > 
> > > Signed-off-by: hans.zhang <18255117159@....com>
> > > ---
> > > Changes since v1-v2:
> > > - Change email number and Signed-off-by
> > > ---
> > >   drivers/pci/controller/cadence/pcie-cadence-ep.c | 3 +--
> > >   drivers/pci/controller/cadence/pcie-cadence.h    | 2 +-
> > >   2 files changed, 2 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/pci/controller/cadence/pcie-cadence-ep.c b/drivers/pci/controller/cadence/pcie-cadence-ep.c
> > > index e0cc4560dfde..0bf4cde34f51 100644
> > > --- a/drivers/pci/controller/cadence/pcie-cadence-ep.c
> > > +++ b/drivers/pci/controller/cadence/pcie-cadence-ep.c
> > > @@ -352,8 +352,7 @@ static void cdns_pcie_ep_assert_intx(struct cdns_pcie_ep *ep, u8 fn, u8 intx,
> > >   	spin_unlock_irqrestore(&ep->lock, flags);
> > >   	offset = CDNS_PCIE_NORMAL_MSG_ROUTING(MSG_ROUTING_LOCAL) |
> > > -		 CDNS_PCIE_NORMAL_MSG_CODE(msg_code) |
> > > -		 CDNS_PCIE_MSG_NO_DATA;
> > > +		 CDNS_PCIE_NORMAL_MSG_CODE(msg_code);
> > >   	writel(0, ep->irq_cpu_addr + offset);
> > >   }
> > > diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
> > > index f5eeff834ec1..39ee9945c903 100644
> > > --- a/drivers/pci/controller/cadence/pcie-cadence.h
> > > +++ b/drivers/pci/controller/cadence/pcie-cadence.h
> > > @@ -246,7 +246,7 @@ struct cdns_pcie_rp_ib_bar {
> > >   #define CDNS_PCIE_NORMAL_MSG_CODE_MASK		GENMASK(15, 8)
> > >   #define CDNS_PCIE_NORMAL_MSG_CODE(code) \
> > >   	(((code) << 8) & CDNS_PCIE_NORMAL_MSG_CODE_MASK)
> > > -#define CDNS_PCIE_MSG_NO_DATA			BIT(16)
> > > +#define CDNS_PCIE_MSG_DATA			BIT(16)
> > 
> > Oops! So how did you spot the issue? Did INTx triggering ever worked? RC should
> > have reported it as malformed TLP isn't it?
> > 
> In our first generation SOC, sending messages did not work, and the length
> of messages was all 1. Cadence fixed this problem in the second generation
> SOC. And I have verified in the EMU environment that it is OK to send
> various messages, including INTx.
> 
> And that's what Cadence's release documentation says:
> axi_s_awaddr bits 16 is 1 for MSG with data and 0 for MSG without data.

I'm confused now. So the change in axi_s_awaddr bit applies to second generation
SoCs only? What about the first ones?

Are you saying that the first generation SoCs can never send any message TLPs at
all? This sounds horrible.

- Mani

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