From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Date: Tue, 21 Aug 2018 06:02:27 +0200 Subject: [U-Boot] [PATCH] pci: Support parsing PCI controller DT subnodes In-Reply-To: References: <20180810120135.GH29229@bill-the-cat> <972158e3-e0bd-4798-699f-06a97d7100d1@gmail.com> <98561a43-18bf-3c76-d3c6-3320cdafdf4b@gmail.com> <7a1aa6ed-7ddd-551a-f445-171465dbbe46@gmail.com> <92b4b0cc-b3fb-45c8-20f9-a232c2891edf@gmail.com> <20180815112540.GG30947@bill-the-cat> Message-ID: <6aa50a30-df29-07fe-4d12-f9cbdae82df1@gmail.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 08/21/2018 05:46 AM, Bin Meng wrote: > Hi Simon, > > On Tue, Aug 21, 2018 at 3:29 AM, Simon Glass wrote: >> Hi Marek, >> >> On 20 August 2018 at 12:42, Marek Vasut wrote: >>> >>> On 08/20/2018 06:57 PM, Simon Glass wrote: >>>> Hi Bin, >>>> >>>> On 16 August 2018 at 19:51, Bin Meng wrote: >>>>> Hi Marek, >>>>> >>>>> On Thu, Aug 16, 2018 at 7:47 PM, Marek Vasut wrote: >>>>>> On 08/15/2018 01:25 PM, Tom Rini wrote: >>>>>>> On Wed, Aug 15, 2018 at 06:19:25PM +0800, Bin Meng wrote: >>>>>>>> Hi Marek, >>>>>>>> >>>>>>>> On Wed, Aug 15, 2018 at 5:22 PM, Marek Vasut wrote: >>>>>>>>> On 08/14/2018 11:40 AM, Bin Meng wrote: >>>>>>>>>> Hi Marek, >>>>>>>>>> >>>>>>>>>> On Tue, Aug 14, 2018 at 4:55 PM, Marek Vasut wrote: >>>>>>>>>>> On 08/14/2018 03:46 AM, Bin Meng wrote: >>>>>>>>>>>> Hi Marek, >>>>>>>>>>>> >>>>>>>>>>>> On Mon, Aug 13, 2018 at 9:46 PM, Marek Vasut wrote: >>>>>>>>>>>>> On 08/13/2018 04:24 AM, Bin Meng wrote: >>>>>>>>>>>>>> Hi Marek, >>>>>>>>>>>>>> >>>>>>>>>>>>>> On Fri, Aug 10, 2018 at 8:38 PM, Marek Vasut wrote: >>>>>>>>>>>>>>> On 08/10/2018 02:01 PM, Tom Rini wrote: >>>>>>>>>>>>>>>> On Wed, Aug 08, 2018 at 09:37:25PM +0200, Marek Vasut wrote: >>>>>>>>>>>>>>>>> On 08/08/2018 05:32 PM, Bin Meng wrote: >>>>>>>>>>>>>>>>>> Hi Marek, >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> On Wed, Aug 8, 2018 at 10:33 PM, Marek Vasut wrote: >>>>>>>>>>>>>>>>>>> On 08/08/2018 03:39 PM, Bin Meng wrote: >>>>>>>>>>>>>>>>>>>> Hi Marek, >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> On Wed, Aug 8, 2018 at 9:24 PM, Marek Vasut wrote: >>>>>>>>>>>>>>>>>>>>> On 08/08/2018 03:14 PM, Bin Meng wrote: >>>>>>>>>>>>>>>>>>>>>> Hi Marek, >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> On Wed, Aug 8, 2018 at 9:03 PM, Marek Vasut wrote: >>>>>>>>>>>>>>>>>>>>>>> The PCI controller can have DT subnodes describing extra properties >>>>>>>>>>>>>>>>>>>>>>> of particular PCI devices, ie. a PHY attached to an EHCI controller >>>>>>>>>>>>>>>>>>>>>>> on a PCI bus. This patch parses those DT subnodes and assigns a node >>>>>>>>>>>>>>>>>>>>>>> to the PCI device instance, so that the driver can extract details >>>>>>>>>>>>>>>>>>>>>>> from that node and ie. configure the PHY using the PHY subsystem. >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> Signed-off-by: Marek Vasut >>>>>>>>>>>>>>>>>>>>>>> Cc: Simon Glass >>>>>>>>>>>>>>>>>>>>>>> --- >>>>>>>>>>>>>>>>>>>>>>> drivers/pci/pci-uclass.c | 14 ++++++++++++++ >>>>>>>>>>>>>>>>>>>>>>> 1 file changed, 14 insertions(+) >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c >>>>>>>>>>>>>>>>>>>>>>> index 46e9c71bdf..306bea0dbf 100644 >>>>>>>>>>>>>>>>>>>>>>> --- a/drivers/pci/pci-uclass.c >>>>>>>>>>>>>>>>>>>>>>> +++ b/drivers/pci/pci-uclass.c >>>>>>>>>>>>>>>>>>>>>>> @@ -662,6 +662,8 @@ static int pci_find_and_bind_driver(struct udevice *parent, >>>>>>>>>>>>>>>>>>>>>>> for (id = entry->match; >>>>>>>>>>>>>>>>>>>>>>> id->vendor || id->subvendor || id->class_mask; >>>>>>>>>>>>>>>>>>>>>>> id++) { >>>>>>>>>>>>>>>>>>>>>>> + ofnode node; >>>>>>>>>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>>>>>>>>> if (!pci_match_one_id(id, find_id)) >>>>>>>>>>>>>>>>>>>>>>> continue; >>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>> @@ -691,6 +693,18 @@ static int pci_find_and_bind_driver(struct udevice *parent, >>>>>>>>>>>>>>>>>>>>>>> goto error; >>>>>>>>>>>>>>>>>>>>>>> debug("%s: Match found: %s\n", __func__, drv->name); >>>>>>>>>>>>>>>>>>>>>>> dev->driver_data = find_id->driver_data; >>>>>>>>>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>>>>>>>>> + dev_for_each_subnode(node, parent) { >>>>>>>>>>>>>>>>>>>>>>> + phys_addr_t df, size; >>>>>>>>>>>>>>>>>>>>>>> + df = ofnode_get_addr_size(node, "reg", &size); >>>>>>>>>>>>>>>>>>>>>>> + >>>>>>>>>>>>>>>>>>>>>>> + if (PCI_FUNC(df) == PCI_FUNC(bdf) && >>>>>>>>>>>>>>>>>>>>>>> + PCI_DEV(df) == PCI_DEV(bdf)) { >>>>>>>>>>>>>>>>>>>>>>> + dev->node = node; >>>>>>>>>>>>>>>>>>>>>>> + break; >>>>>>>>>>>>>>>>>>>>>>> + } >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> The function pci_find_and_bind_driver() is supposed to bind devices >>>>>>>>>>>>>>>>>>>>>> that are NOT in the device tree. Adding device tree access in this >>>>>>>>>>>>>>>>>>>>>> routine is quite odd. You can add the EHCI controller that need such >>>>>>>>>>>>>>>>>>>>>> PHY subnodes in the device tree and there is no need to modify >>>>>>>>>>>>>>>>>>>>>> anything I believe. If you are looking for an example, please check >>>>>>>>>>>>>>>>>>>>>> pciuart0 in arch/x86/dts/crownbay.dts. >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> Well this does not work for me, the EHCI PCI doesn't get a DT node >>>>>>>>>>>>>>>>>>>>> assigned, check r8a7794.dtsi for the PCI devices I use. >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> I think that's because you don't specify a "compatible" string for >>>>>>>>>>>>>>>>>>>> these two EHCI PCI nodes. >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> That's perfectly fine, why should I specify it ? Linux has no problem >>>>>>>>>>>>>>>>>>> with it either. >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> Without a "compatible" string, DM does not bind any device in the >>>>>>>>>>>>>>>>>> device tree to a driver, hence no device node created. This is not >>>>>>>>>>>>>>>>>> Linux. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> DT is NOT Linux specific, it is OS-agnostic, DT describes hardware and >>>>>>>>>>>>>>>>> hardware only. If U-Boot cannot parse DT correctly, U-Boot is broken and >>>>>>>>>>>>>>>>> must be fixed. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> This is a fix. If there is a better fix, I am open to it. >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> DT should but isn't always OS agnostic. DTS files that reside in the >>>>>>>>>>>>>>>> Linux Kernel are in practice is Linux-centric with the expectation that >>>>>>>>>>>>>>>> even if you could solve a given problem with valid DTS changes you make >>>>>>>>>>>>>>>> whatever is parsing it do additional logic instead. That, >>>>>>>>>>>>>>>> approximately, is what your patch is doing. If you added some HW >>>>>>>>>>>>>>>> description information to the dtsi file everything would work as >>>>>>>>>>>>>>>> expected as your DTS is describing the hardware and U-Boot is reading >>>>>>>>>>>>>>>> that description and figuring out what to do with it. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Yes, you need additional logic to match the PCI controller subnode in DT >>>>>>>>>>>>>>> with PCI device BFD, that's expected. You do NOT need extra compatibles, >>>>>>>>>>>>>>> the PCI bus gives you enough information to match a driver on them. In >>>>>>>>>>>>>>> fact, adding a compatible can interfere with this matching. >>>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> Please, read U-Boot's doc/driver-model/pci-info.txt. You really don't >>>>>>>>>>>>>> understand current implementation in U-Boot. In short, U-Boot supports >>>>>>>>>>>>>> two scenarios for PCI driver binding: >>>>>>>>>>>>> >>>>>>>>>>>>> That documentation is wrong and needs to be fixed. The compatible is >>>>>>>>>>>>> optional. >>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> No it is not wrong. The documentation reflects the update-to-date >>>>>>>>>>>> U-Boot support of PCI bus with DM. >>>>>>>>>>> >>>>>>>>>>> Which is incomplete, as it cannot parse subnodes without compatible strings. >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> No, it's by design, as I said many times. It can support parsing >>>>>>>>>> subnodes with a "compatible" string existence. >>>>>>>>> >>>>>>>>> It can support parsing subnodes with a "compatible" string existence AND >>>>>>>>> It can NOT support parsing subnodes without a "compatible" string >>>>>>>>> existence THUS It is incomplete. >>>>>>>>> >>>>>>>>>>>>>> - Declare a PCI device in the device tree. That requires specifying a >>>>>>>>>>>>>> 'compatible' string as well as 'reg' property as defined by the 'PCI >>>>>>>>>>>>>> Bus Binding' spec. DM uses the 'compatible' string to bind the driver >>>>>>>>>>>>>> for the device. >>>>>>>>>>>>>> - Don't declare a PCI device in the device tree. Instead, using >>>>>>>>>>>>>> U_BOOT_PCI_DEVICE() to declare a device and driver mapping. >>>>>>>>>>>>>> >>>>>>>>>>>>>> You can choose either two when you support PCI devices on your board, >>>>>>>>>>>>>> but you cannot mix both support together and make them a mess. In this >>>>>>>>>>>>>> patch, you hacked pci_find_and_bind_driver() which is the 2nd scenario >>>>>>>>>>>>>> to support the 1st scenario. >>>>>>>>>>>>> >>>>>>>>>>>>> Again, the DT contains all the required information to bind the node and >>>>>>>>>>>>> the driver instance. Clearly, we need option 3 for this. >>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Then that's a new design proposal. Anything that wants to mess up >>>>>>>>>>>> current design is a hack. >>>>>>>>>>> >>>>>>>>>>> That means every single patch anyone submits is now a hack ? Please ... >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> I never said "every single patch anyone submits is now a hack". "You >>>>>>>>>> are inserting words into my mouth and I dislike that." I said your >>>>>>>>>> current patch is against the design, and mess up current design which >>>>>>>>>> is a hack. >>>>>>>>> >>>>>>>>> But then every patch which changes the behavior is against "the design" >>>>>>>>> and thus is a hack. Ultimately, most improvements would be considered a >>>>>>>>> hack. >>>>>>>> >>>>>>>> No it depends. For this case, there are two options that DM PCI >>>>>>>> currently provides. You created a 3rd option that bring option 1 and 2 >>>>>>>> together in a mixed way, yet without any documenting and additional >>>>>>>> other changes. If you posted such changes in a series and have all >>>>>>>> stuff well considered, I would not consider it a hack, but a proposed >>>>>>>> design change. >>>>>>> >>>>>>> Also, the design document is not immutable and can and should be updated >>>>>>> as needed to match changes in the code. >>>>>> >>>>>> So what is the conclusion here ? Patch the design document and apply >>>>>> this patch as is ? >>>>>> >>>>> >>>>> I think we should see Simon's comments before we move forward. The >>>>> proposal I made before should come in a series, not just >>>>> documentation. >>>> >>>> This thread is too long :-) >>>> > > Yes, too long discussion :) > >>>> From what I understand, Marek and Bin are discussing whether a >>>> compatible string is needed to bind a driver. >>>> >>>> Generally it is. But with PCI and USB we have a search mechanism which >>>> can be used instead. >>>> >>>> The patch Marek submitted does not seems at all desirable to me. >>> >>> Can you explain why ? >> >> We already have a compatible string as the standard way to attach >> drivers to devices. >> >> For PCI, we already have PCI_DEVICE() and friends for when we can >> attach a driver for a PCI device without using a compatible string. >> >> Both of these are defined in the DT specification. >> >> The patch seems to be a rework of PCI_DEVICE() and I cannot why it is necessary. >> >>> >>>> I would like to see what Bin proposes. >>> >>> Me too, so far I only see "not Marek's patch" and no real alternative. >> >> Bin, do you have a patch you can share? > > No, I don't have any patch series for now, although I offered to work > on a series to implement my proposal. I haven't started it as I wanted > to hear your thoughts. The proposal I made is to satisfy the > requirement that Marek insisted on. Basically Marek thought current DM > PCI implementation is wrong to ask for a "compatible" string of a PCI > device in the device tree, because he thought adding "compatible" to > DT is invalid and Linux does not do that either. While I disagree we > have to 100% follow Linux's implementation, I am still open for any > possible design changes, if that's the preferable practice in U-Boot > (but we have to make it clear and document this officially somewhere). > > The proposal I made is: > > * Keep pci-uclass driver's post_bind() and child_post_bind() only for > Sandbox configuration > * Keep the call to pci_bus_find_devfn() in pci_bind_bus_devices() only > for Sandbox configuration > * Sandbox is special. We should limit the mechanism of matching PCI > emulation device via "compatible" to sandbox only The above three points can be done separately and I don't care about this too much. > * Assign the DT node to the bound device in pci_find_and_bind_driver() > if there is a valid PCI "reg" encoding for a specific PCI device in > the device tree This is what this patch does. And in fact, I have real hardware which needs this patch to be useful and on which I can test if this works. > * Create DM PCI test case against the DT node assignment > * Remove all compatible string in U-Boot's PCI device drivers: eg: > ehci_pci_ids[], xhci_pci_ids[], etc. IOW, all PCI device drivers > should only use U_BOOT_PCI_DEVICE(), aka the original U-Boot option 2 > * Fork a "pci-ns16550" driver to support U_BOOT_PCI_DEVICE(), as > currently PCI ns16550 device driver uses "compatible" string to do the > matching, and update crownbay.dts and galileo.dts (so far I only know > two boards are using PCI ns16550 serial port) > * Make sure all DM PCI test cases are not broken > * Document all of the above changes in doc/driver-model/pci-info.txt I think you're just adding completely orthogonal stuff to this 5-liner patch into the list and overly complicate the situation. Sure, if you want to do all this, go ahead, but I don't see how this prevents this particular patch from being applied , except maybe for the documentation tweak. -- Best regards, Marek Vasut