Hi Simon,
On Tue, Aug 21, 2018 at 3:29 AM, Simon Glass sjg@chromium.org wrote:
Hi Marek,
On 20 August 2018 at 12:42, Marek Vasut marek.vasut@gmail.com wrote:
On 08/20/2018 06:57 PM, Simon Glass wrote:
Hi Bin,
On 16 August 2018 at 19:51, Bin Meng bmeng.cn@gmail.com wrote:
Hi Marek,
On Thu, Aug 16, 2018 at 7:47 PM, Marek Vasut marek.vasut@gmail.com 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 marek.vasut@gmail.com wrote: >> On 08/14/2018 11:40 AM, Bin Meng wrote: >>> Hi Marek, >>> >>> On Tue, Aug 14, 2018 at 4:55 PM, Marek Vasut marek.vasut@gmail.com wrote: >>>> On 08/14/2018 03:46 AM, Bin Meng wrote: >>>>> Hi Marek, >>>>> >>>>> On Mon, Aug 13, 2018 at 9:46 PM, Marek Vasut marek.vasut@gmail.com wrote: >>>>>> On 08/13/2018 04:24 AM, Bin Meng wrote: >>>>>>> Hi Marek, >>>>>>> >>>>>>> On Fri, Aug 10, 2018 at 8:38 PM, Marek Vasut marek.vasut@gmail.com 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 marek.vasut@gmail.com wrote: >>>>>>>>>>>> On 08/08/2018 03:39 PM, Bin Meng wrote: >>>>>>>>>>>>> Hi Marek, >>>>>>>>>>>>> >>>>>>>>>>>>> On Wed, Aug 8, 2018 at 9:24 PM, Marek Vasut marek.vasut@gmail.com wrote: >>>>>>>>>>>>>> On 08/08/2018 03:14 PM, Bin Meng wrote: >>>>>>>>>>>>>>> Hi Marek, >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> On Wed, Aug 8, 2018 at 9:03 PM, Marek Vasut marek.vasut@gmail.com 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 marek.vasut+renesas@gmail.com >>>>>>>>>>>>>>>> Cc: Simon Glass sjg@chromium.org >>>>>>>>>>>>>>>> --- >>>>>>>>>>>>>>>> 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
Regards, Bin