From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Glass Date: Tue, 21 Aug 2018 11:32:02 -0600 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: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de 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. Regards, Simon