From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bin Meng Date: Tue, 21 Aug 2018 12:15:04 +0800 Subject: [U-Boot] [PATCH] pci: Support parsing PCI controller DT subnodes In-Reply-To: <6aa50a30-df29-07fe-4d12-f9cbdae82df1@gmail.com> 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> <6aa50a30-df29-07fe-4d12-f9cbdae82df1@gmail.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Marek, On Tue, Aug 21, 2018 at 12:02 PM, Marek Vasut wrote: > 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. > That's my concern. Only doing this created confusing and incomplete design. Yes, you probably don't care about this. But I care about this as it impacts some other things like PCI uart driver which is used by some x86 boards. >> * 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. > You can do this in your own fork. Nothing prevents you from doing that. >> * 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. Please, think from the maintainer perspective. It's nothing related to number of LOCs. It's that we need create a clean design. You probably don't want someone just submits a single patch that changed current USB design without a full consideration on all possible impacts. Regards, Bin