Message-ID: <e7a84453-7677-6692-8662-ef719158bfbf@loongson.cn>
Date:   Fri, 21 Jul 2023 16:13:54 +0800
From:   Yinbo Zhu <zhuyinbo@...ngson.cn>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Minas Harutyunyan <hminas@...opsys.com>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jianmin Lv <lvjianmin@...ngson.cn>,
        wanghongliang@...ngson.cn, Liu Peibao <liupeibao@...ngson.cn>,
        loongson-kernel@...ts.loongnix.cn, zhuyinbo@...ngson.cn
Subject: Re: [PATCH v2] usb: dwc2: add pci_device_id driver_data parse support


Hi greg k-h,


I'm sorry to bother you,  I want to request your opinion on what I have 
said.


Thanks,

Yinbo


在 2023/6/14 上午11:55, zhuyinbo 写道:
>
>
> 在 2023/6/13 下午6:19, Greg Kroah-Hartman 写道:
>> On Mon, Jun 12, 2023 at 02:51:05PM +0800, zhuyinbo wrote:
>>>
>>>
>>> 在 2023/6/9 下午5:31, Greg Kroah-Hartman 写道:
>>>> On Fri, Jun 09, 2023 at 11:25:15AM +0200, Greg Kroah-Hartman wrote:
>>>>> On Fri, Jun 09, 2023 at 05:07:03PM +0800, zhuyinbo wrote:
>>>>>>
>>>>>>
>>>>>> 在 2023/6/9 下午2:13, Greg Kroah-Hartman 写道:
>>>>>>> On Fri, Jun 09, 2023 at 10:50:47AM +0800, Yinbo Zhu wrote:
>>>>>>>> The dwc2 driver has everything we need to run in PCI mode except
>>>>>>>> for pci_device_id driver_data parse.  With that to set Loongson
>>>>>>>> dwc2 element and added identified as PCI_VENDOR_ID_LOONGSON
>>>>>>>> and PCI_DEVICE_ID_LOONGSON_DWC2 in dwc2_pci_ids, the Loongson
>>>>>>>> dwc2 controller will work.
>>>>>>>>
>>>>>>>> Signed-off-by: Yinbo Zhu <zhuyinbo@...ngson.cn>
>>>>>>>> ---
>>>>>>>> Change in v2:
>>>>>>>>         1. Move the dwc2 pci ID from pci_ids.h to params.c.
>>>>>>>>         2. Add some code logic to ensure that the current 
>>>>>>>> device is
>>>>>>>>            a PCI device.
>>>>>>>>         3. Fix the compile issue when dwc2 pci driver as module.
>>>>>>>>
>>>>>>>>     drivers/usb/dwc2/core.h   |  1 +
>>>>>>>>     drivers/usb/dwc2/params.c | 39 
>>>>>>>> ++++++++++++++++++++++++++++++++++++++-
>>>>>>>>     drivers/usb/dwc2/pci.c    | 14 +-------------
>>>>>>>>     3 files changed, 40 insertions(+), 14 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
>>>>>>>> index 0bb4c0c845bf..c92a1da46a01 100644
>>>>>>>> --- a/drivers/usb/dwc2/core.h
>>>>>>>> +++ b/drivers/usb/dwc2/core.h
>>>>>>>> @@ -1330,6 +1330,7 @@ irqreturn_t dwc2_handle_common_intr(int 
>>>>>>>> irq, void *dev);
>>>>>>>>     /* The device ID match table */
>>>>>>>>     extern const struct of_device_id dwc2_of_match_table[];
>>>>>>>>     extern const struct acpi_device_id dwc2_acpi_match[];
>>>>>>>> +extern const struct pci_device_id dwc2_pci_ids[];
>>>>>>>>     int dwc2_lowlevel_hw_enable(struct dwc2_hsotg *hsotg);
>>>>>>>>     int dwc2_lowlevel_hw_disable(struct dwc2_hsotg *hsotg);
>>>>>>>> diff --git a/drivers/usb/dwc2/params.c b/drivers/usb/dwc2/params.c
>>>>>>>> index 21d16533bd2f..6b68a8830781 100644
>>>>>>>> --- a/drivers/usb/dwc2/params.c
>>>>>>>> +++ b/drivers/usb/dwc2/params.c
>>>>>>>> @@ -7,9 +7,14 @@
>>>>>>>>     #include <linux/module.h>
>>>>>>>>     #include <linux/of_device.h>
>>>>>>>>     #include <linux/usb/of.h>
>>>>>>>> +#include <linux/pci_ids.h>
>>>>>>>> +#include <linux/pci.h>
>>>>>>>>     #include "core.h"
>>>>>>>> +#define PCI_PRODUCT_ID_HAPS_HSOTG    0xabc0
>>>>>>>> +#define PCI_DEVICE_ID_LOONGSON_DWC2    0x7a04
>>>>>>>> +
>>>>>>>>     static void dwc2_set_bcm_params(struct dwc2_hsotg *hsotg)
>>>>>>>>     {
>>>>>>>>         struct dwc2_core_params *p = &hsotg->params;
>>>>>>>> @@ -55,6 +60,14 @@ static void dwc2_set_jz4775_params(struct 
>>>>>>>> dwc2_hsotg *hsotg)
>>>>>>>> !device_property_read_bool(hsotg->dev, "disable-over-current");
>>>>>>>>     }
>>>>>>>> +static void dwc2_set_loongson_params(struct dwc2_hsotg *hsotg)
>>>>>>>> +{
>>>>>>>> +    struct dwc2_core_params *p = &hsotg->params;
>>>>>>>> +
>>>>>>>> +    p->phy_utmi_width = 8;
>>>>>>>> +    p->power_down = DWC2_POWER_DOWN_PARAM_PARTIAL;
>>>>>>>> +}
>>>>>>>> +
>>>>>>>>     static void dwc2_set_x1600_params(struct dwc2_hsotg *hsotg)
>>>>>>>>     {
>>>>>>>>         struct dwc2_core_params *p = &hsotg->params;
>>>>>>>> @@ -281,6 +294,23 @@ const struct acpi_device_id 
>>>>>>>> dwc2_acpi_match[] = {
>>>>>>>>     };
>>>>>>>>     MODULE_DEVICE_TABLE(acpi, dwc2_acpi_match);
>>>>>>>> +const struct pci_device_id dwc2_pci_ids[] = {
>>>>>>>> +    {
>>>>>>>> +        PCI_DEVICE(PCI_VENDOR_ID_SYNOPSYS, 
>>>>>>>> PCI_PRODUCT_ID_HAPS_HSOTG),
>>>>>>>> +    },
>>>>>>>> +    {
>>>>>>>> +        PCI_DEVICE(PCI_VENDOR_ID_STMICRO,
>>>>>>>> +               PCI_DEVICE_ID_STMICRO_USB_OTG),
>>>>>>>> +    },
>>>>>>>> +    {
>>>>>>>> +        PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, 
>>>>>>>> PCI_DEVICE_ID_LOONGSON_DWC2),
>>>>>>>> +        .driver_data = (unsigned long)dwc2_set_loongson_params,
>>>>>>>> +    },
>>>>>>>> +    { /* end: all zeroes */ }
>>>>>>>> +};
>>>>>>>> +MODULE_DEVICE_TABLE(pci, dwc2_pci_ids);
>>>>>>>> +EXPORT_SYMBOL_GPL(dwc2_pci_ids);
>>>>>>>> +
>>>>>>>>     static void dwc2_set_param_otg_cap(struct dwc2_hsotg *hsotg)
>>>>>>>>     {
>>>>>>>>         switch (hsotg->hw_params.op_mode) {
>>>>>>>> @@ -927,13 +957,20 @@ int dwc2_init_params(struct dwc2_hsotg 
>>>>>>>> *hsotg)
>>>>>>>>         if (match && match->data) {
>>>>>>>>             set_params = match->data;
>>>>>>>>             set_params(hsotg);
>>>>>>>> -    } else {
>>>>>>>> +    } else if (!match) {
>>>>>>>>             const struct acpi_device_id *amatch;
>>>>>>>> +        const struct pci_device_id *pmatch = NULL;
>>>>>>>>             amatch = acpi_match_device(dwc2_acpi_match, 
>>>>>>>> hsotg->dev);
>>>>>>>>             if (amatch && amatch->driver_data) {
>>>>>>>>                 set_params = (set_params_cb)amatch->driver_data;
>>>>>>>>                 set_params(hsotg);
>>>>>>>> +        } else if (!amatch)
>>>>>>>> +            pmatch = pci_match_id(dwc2_pci_ids, 
>>>>>>>> to_pci_dev(hsotg->dev->parent));
>>>>>>>
>>>>>>> At this point in time, how can you guarantee that the parent device
>>>>>>> really is a PCI one?  This function is being called from a platform
>>>>>>> device callback, and platform devices should NEVER be a child of 
>>>>>>> a PCI
>>>>>>> device, as that's not how PCI or platform devices work.
>>>>>>>
>>>>>>> So how is this even possible?
>>>>>>>
>>>>>>> confused,
>>>>>>>
>>>>>>
>>>>>>
>>>>>> Hi greg k-h,
>>>>>>
>>>>>> My current considerations are based on that the dwc2 drivers support
>>>>>> three types of devices, they are Platform device / ACPI device / PCI
>>>>>> device, and The dwc2/platform.c can all cover the three type dwc2
>>>>>> device, no matter how it is registered.
>>>>>>
>>>>>> So, when a dwc2 device wasn't platform device and acpi device and It
>>>>>> will be a PCI device, and the the dwc2/pci.c will register a dwc2
>>>>>> platform device that dwc2 device is a device that in 
>>>>>> dwc2/platform.c's
>>>>>> dwc2_driver_probe.  the "&dwc2->dev->parent" is the 
>>>>>> "hsotg->dev->parent"
>>>>>> and it was also the &pci->dev.
>>>>>
>>>>> That's wrong, a PCI device should NEVER register a platform device 
>>>>> under
>>>>> it, as obviously it's not a platform device at all.
>>>>>
>>>>> So please work to fix that layering violation here, as that's not
>>>>> correct and will cause problems as you are showing here.
>>>>>
>>>>>> So, We can use "to_pci_dev(hsotg->dev->parent)" to gain a dwc2 pci
>>>>>> device.
>>>>>
>>>>> No, not if the parent is something else as you have no way of knowing
>>>>> this at this point in time.
>>>>>
>>>>>>
>>>>>> 1)  DWC2 PCI device driver (drivers/usb/dwc2/pci.c) :
>>>>>>
>>>>>> static int dwc2_pci_probe(struct pci_dev *pci,
>>>>>>                             const struct pci_device_id *id)
>>>>>> {
>>>>>> ...
>>>>>>           struct platform_device  *dwc2;
>>>>>> ...
>>>>>>           struct device           *dev = &pci->dev;
>>>>>> ...
>>>>>>     dwc2 = platform_device_alloc("dwc2", PLATFORM_DEVID_AUTO);
>>>>>>                   //"dwc2" was used to match dwc2 platform driver
>>>>>
>>>>> This needs to be fixed, it's not ok at all.  Just use the real PCI
>>>>> device here please.
>>>>
>>>> Also, to be fair, you didn't cause this problem, I missed it 
>>>> previously.
>>>> But fixing it is essential, and will be required in order to get your
>>>> changes to work properly.  Sorry about that.
>>>>
>>>
>>>
>>> Hi greg k-h,
>>>
>>> Actually,  the dwc2/pci.c's  platform_device_add(dwc2) was create a
>>> platform device called "dwc2"  ensure dwc2/platform's dwc2_driver_probe
>>> function can be called. After all, the dwc2/platform's 
>>> dwc2_driver_probe
>>> is the one that truly initializes the dwc2 controller. In addition, the
>>> same applies to dwc3 code.
>>
>> Yes, it does create a platform device, but ALSO a real platform device
>> could be present in the system for the driver, one that is NOT a child
>> of a PCI device, right?
>
>
> I don't get it that why need dwc2 was a child of pci. and I just need
> the dwc2->dev.parent's parent device was a child of dwc2 pci device.
> If my patch conditions are met (match and amatch was NULL), this always
> seems to hold true.
>
> dwc2_pci_probe ()
> {
> struct platform_device  *dwc2;
> struct device *dev = &pci->dev;
> dwc2->dev.parent = dev;
> platform_device_add(dwc2);
> }
>
>>
>> It's not this way with your system, but it could be that way for many
>> others, right?  And if so, the assumption that you can just poke around
>> in the parent device and assume that you know what bus it is on is just
>> wrong and will break things.
>
>
> What you said about "system" that is unrelated to the kernel driver? I
> think it should be system independent and it depends entirely on the
> kernel driver, for the driver, everyone is the same. the behavior of the
> driver is known, and currently I have not found any other risks it
> poses.  Additionally, the key is that the issue that my patch is
> addressing is a common issue. For example, if the following devices are
> designed as PCI devices on hardware, they will always encounter the same
> problem.
>
> const struct of_device_id dwc2_of_match_table[] = {
>         { .compatible = "brcm,bcm2835-usb", .data = 
> dwc2_set_bcm_params },
>         { .compatible = "hisilicon,hi6220-usb", .data = 
> dwc2_set_his_params },
>         { .compatible = "ingenic,jz4775-otg", .data = 
> dwc2_set_jz4775_params },
>         { .compatible = "ingenic,jz4780-otg", .data = 
> dwc2_set_jz4775_params },
>         { .compatible = "ingenic,x1000-otg", .data = 
> dwc2_set_jz4775_params },
>         { .compatible = "ingenic,x1600-otg", .data = 
> dwc2_set_x1600_params },
>         { .compatible = "ingenic,x1700-otg", .data = 
> dwc2_set_x1600_params },
>         { .compatible = "ingenic,x1830-otg", .data = 
> dwc2_set_x1600_params },
>         { .compatible = "ingenic,x2000-otg", .data = 
> dwc2_set_x2000_params },
>         { .compatible = "rockchip,rk3066-usb", .data = 
> dwc2_set_rk_params },
>         { .compatible = "lantiq,arx100-usb", .data = 
> dwc2_set_ltq_params },
>         { .compatible = "lantiq,xrx200-usb", .data = 
> dwc2_set_ltq_params },
>
>>
>> You should NEVER be poking around in the information for the parent
>> device, UNLESS you have just created the child device yourself and the
>> ONLY code path is one that you have full control over.
>>
>> Does that make more sense?
>
>
> Yes, but it seems inappropriate for dwc2. For this, please allow me to 
> parse some of my comments in v1:
>
>
> Actually, I use pci_match_id was due to I noticed that xhci-pci.c,
> ehci-pci.c and ohci-pci.c was all use it . and I don't use it in
> dwc2/pci.c was considering set dwc2 element need dpend on elements.c and
> platform.c, and usb driver (ohci,echi,xhci) was a relatively
> indepent device driver when to operate usb controler. but dwc2 was not.
>
> If I fource the element setting of dwc2 element in dwc2/pci.c. It will 
> be following case. This will cause problems with element-initial
> function or element-check function.
>
> 1. initial dwc2 element.
> 2. check the setting of dwc2 element whether was suitable
> 3. set dwc2 element.
>
> or
>
> 1. set dwc2 element.
> 2. initial dwc2 element.
> 3. check the setting of dwc2 element whether was suitable
>
> The corresponding code call process as follows:
>
> 1. dwc2_set_default_params(hsotg);
> 2. dwc2_get_device_properties(hsotg);
> 3. dwc2_check_params(hsotg);
> 4. dwc2_set_loongson_params;
>
> or
>
> 1. dwc2_set_loongson_params;
> 2. dwc2_set_default_params(hsotg);
> 3. dwc2_get_device_properties(hsotg);
> 4. dwc2_check_params(hsotg);
>
> But the platform dwc2 device or acpi dwc2 device was all following case
> and It seems was correct order.
>
> 1. dwc2_set_default_params(hsotg);
> 2. dwc2_get_device_properties(hsotg);
> 3. dwc2_set_loongson_params;
> 4. dwc2_check_params(hsotg);
>
>
> Thanks,
>
> Yinbo

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