On Wed, Feb 14, 2024 at 11:44:12AM +0530, Manivannan Sadhasivam wrote: > On Fri, Feb 09, 2024 at 12:52:52PM +0300, Serge Semin wrote: > > On Wed, Feb 07, 2024 at 11:02:02AM -0500, Frank Li wrote: > > > On Wed, Feb 07, 2024 at 03:37:30PM +0300, Serge Semin wrote: > > > > On Tue, Feb 06, 2024 at 05:47:26PM -0500, Frank Li wrote: > > > > > On Mon, Feb 05, 2024 at 02:13:37PM -0500, Frank Li wrote: > > > > > > On Mon, Feb 05, 2024 at 06:30:48PM +0000, Rob Herring wrote: > > > > > > > On Sat, Feb 03, 2024 at 01:44:31AM +0300, Serge Semin wrote: > > > > > > > > On Fri, Feb 02, 2024 at 10:11:27AM -0500, Frank Li wrote: > > > > > > > > > Add an outbound iATU-capable memory-region which will be used to send PCIe > > > > > > > > > message (such as PME_Turn_Off) to peripheral. So all platforms can use > > > > > > > > > common method to send out PME_Turn_Off message by using one outbound iATU. > > > > > > > > > > > > > > > > > > Signed-off-by: Frank Li <Frank.Li@xxxxxxx> > > > > > > > > > --- > > > > > > > > > Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml | 4 ++++ > > > > > > > > > 1 file changed, 4 insertions(+) > > > > > > > > > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml b/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml > > > > > > > > > index 022055edbf9e6..25a5420a9ce1e 100644 > > > > > > > > > --- a/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml > > > > > > > > > +++ b/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml > > > > > > > > > @@ -101,6 +101,10 @@ properties: > > > > > > > > > > > > > > > > > Outbound iATU-capable memory-region which will be used to access > > > > > > > > > the peripheral PCIe devices configuration space. > > > > > > > > > const: config > > > > > > > > > + - description: > > > > > > > > > + Outbound iATU-capable memory-region which will be used to send > > > > > > > > > + PCIe message (such as PME_Turn_Off) to peripheral. > > > > > > > > > + const: msg > > > > > > > > > > > > > > > > Note there is a good chance Rob won't like this change. AFAIR he > > > > > > > > already expressed a concern regarding having the "config" reg-name > > > > > > > > describing a memory space within the outbound iATU memory which is > > > > > > > > normally defined by the "ranges" property. Adding a new reg-entry with > > > > > > > > similar semantics I guess won't receive warm welcome. > > > > > > > > > > > > > > I do think it is a bit questionable. Ideally, the driver could > > > > > > > just configure this on its own. However, since we don't describe all of > > > > > > > the CPU address space (that's input to the iATU) already, that's not > > > > > > > going to be possible. I suppose we could fix that, but then config space > > > > > > > would have to be handled differently too. > > > > > > > > > > > > Sorry, I have not understand what your means. Do you means, you want > > > > > > a "cpu-space", for example, 0x8000000 - 0x9000000 for all ATU. > > > > > > > > > > > > Then allocated some space to 'config', 'io', 'memory' and this 'msg'. > > > > > > > > > > @rob: > > > > > > > > > > So far, I think "msg" is feasilbe solution. Or give me some little > > > > > detail direction? > > > > > > > > Found the Rob' note about the iATU-space chunks utilized in the reg > > > > property: > > > > https://lore.kernel.org/linux-pci/CAL_JsqLp7QVgxrAZkW=z38iB7SV5VeWH1O6s+DVCm9p338Czdw@xxxxxxxxxxxxxx/ > > > > > > > > So basically Rob meant back then that > > > > either originally we should have defined a new reg-name like "atu-out" > > > > with the entire outbound iATU CPU-space specified and unpin the > > > > regions like "config"/"ecam"/"msg"/etc from there in the driver > > > > or, well, stick to the chunking further. The later path was chosen > > > > after the patch with the "ecam" reg-name was accepted (see the link > > > > above). > > > > > > > > Really ECAM/config space access, custom TLP messages, legacy interrupt > > > > TLPs, etc are all application-specific features. Each of them is > > > > implemented based on a bit specific but basically the same outbound > > > > iATU engine setup. Thus from the "DT is a hardware description" point > > > > of view it would have been enough to describe the entire outbound iATU > > > > CPU address space and then let the software do the space > > > > reconfiguration in runtime based on it' application needs. > > > > > > There are "addr_space" in EP mode, which useful map out outbound iatu > > > region. We can reuse this name. > > > > > > To keep compatiblity, cut hole from 'config' and 'ranges'. If there are > > > not 'config', we can alloc a 1M(default) from top for 'config', then, 4K > > > (default) for msg, 64K( for IO if not IO region in 'ranges'), left is > > > mem region. We can config each region size by module parameter or drvdata. > > > > > > So we can deprecate 'config', even 'ranges' > > > > Not sure I fully understand what you mean. In anyway the "config" reg > > name is highly utilized by the DW PCIe IP-core instances. We can't > > deprecate it that easily. At least the backwards compatibility must be > > preserved. Moreover "addr_space" is also just a single value reg which > > won't solve a problem with the disjoint DW PCIe outbound iATU memory > > regions. > > > > The "ranges" property is a part of the DT specification. The > > PCI-specific way of the property-based mapping is de-facto a standard > > too. So this can't be deprecated. > > > > > > > > > > > > > * Rob, correct me if am wrong. > > > > > > > > On the other hand it's possible to have more than one disjoint CPU > > > > address region handled by the outbound iATU (especially if there is no > > > > AXI-bridge enabled, see XALI - application transmit client interfaces > > > > in HW manual). Thus having a single reg-property might get to be > > > > inapplicable in some cases. Thinking about that got me to an idea. > > > > What about just extending the PCIe "ranges" property flags > > > > (IORESOURCE_TYPE_BITS) with the new ones in this case indicating the > > > > TLP Msg mapping? Thus we can avoid creating app-specific reg-names and > > > > use the flag to define a custom memory range for the TLP messages > > > > generation. At some point it can be also utilized for the config-space > > > > mapping. What do you think? > > > > > > > > IORESOURCE_TYPE_BITS is 1f, Only 5bit. If extend IORESOURCE_TYPE_BITS, > > > all IORESOURCE_* bit need move. And it is actual MEMORY regain. > > > > No. The lowest four bits aren't flags but the actual value. They are > > retrieved from the PCI-specific memory ranges mapping: > > https://elinux.org/Device_Tree_Usage#PCI_Address_Translation > > https://elixir.bootlin.com/linux/latest/source/arch/sparc/kernel/of_device_64.c#L141 > > https://elixir.bootlin.com/linux/latest/source/arch/sparc/kernel/of_device_32.c#L78 > > Currently only first four out of _sixteen_ values have been defined so > > far. So we can freely use some of the free values for custom TLPs, > > etc. Note the config-space is already defined by the ranges property > > having the 0x0 space code (see the first link above), but it isn't > > currently supported by the PCI subsystem. So at least that option can > > be considered as a ready-to-implement replacement for the "config" > > reg-name. > > > > Agree. But still, the driver has to support both options: "config" reg name and > "ranges", since ammending the binding would be an ABI break. > > > > > > > Or we can use IORESOURCE_BITS (0xff) > > > > > > /* PCI ROM control bits (IORESOURCE_BITS) */ > > > #define IORESOURCE_ROM_ENABLE (1<<0) /* ROM is enabled, same as PCI_ROM_ADDRESS_ENABLE */ > > > #define IORESOURCE_ROM_SHADOW (1<<1) /* Use RAM image, not ROM BAR */ > > > > > > /* PCI control bits. Shares IORESOURCE_BITS with above PCI ROM. */ > > > #define IORESOURCE_PCI_FIXED (1<<4) /* Do not move resource */ > > > #define IORESOURCE_PCI_EA_BEI (1<<5) /* BAR Equivalent Indicator */ > > > > > > we can add > > > > > > IORESOURCE_PRIV_WINDOWS (1<<6) > > > > > > I think previous method was more extendable. How do you think? > > > > IMO extending the PCIe "ranges" property semantics looks more > > promising, more flexible and more portable across various PCIe > > controllers. But the most importantly is what Rob and Bjorn think > > about that, not me. > > > > IMO, using the "ranges" property to allocate arbitrary memory region should be > the way forward, since it has almost all the info needed by the drivers to > allocate the memory regions. > > But for the sake of DT backwards compatiblity, we have to keep supporting the > existing reg entries (addr_space, et al.), because "ranges" is not a required > property for EP controllers. I don't know that its worth the effort to carry both. Maybe if it is useful on more than just DW host. I believe we had config space in ranges at some point on some binding and moved away from that. I forget the reasoning. Rob
