From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Glass Date: Tue, 21 Aug 2018 12:29:51 -0600 Subject: [U-Boot] [PATCH] pci: Support parsing PCI controller DT subnodes In-Reply-To: <8a26296f-bce7-eeb7-8013-e3d45ac69d9f@gmail.com> References: <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> <8a26296f-bce7-eeb7-8013-e3d45ac69d9f@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 21 August 2018 at 12:26, Marek Vasut wrote: > > On 08/21/2018 07:32 PM, Simon Glass wrote: > > Hi Bin, > > > > On 20 August 2018 at 21:46, 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 > >> * 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 > >> * 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 > >> > > > > Thanks very much for all the info. But I don't understand why we want > > to remove compatible strings? They are part of the DT specification. > > Unrelated orthogonal cleanup / optimization IMO. So can you just add a compatible string and everything works? Regards, Simon