+Tom for question below
Hi,
On 20 July 2017 at 03:40, Marek Vasut marex@denx.de wrote:
On 07/20/2017 11:38 AM, Bin Meng wrote:
+Simon,
On Thu, Jul 20, 2017 at 5:00 PM, Marek Vasut marex@denx.de wrote:
On 07/20/2017 09:49 AM, Masahiro Yamada wrote:
2017-07-20 2:33 GMT+09:00 Marek Vasut marex@denx.de:
On 07/19/2017 05:38 PM, Masahiro Yamada wrote:
2017-07-15 21:57 GMT+09:00 Marek Vasut marex@denx.de: > On 07/15/2017 01:30 AM, Benoît Thébaudeau wrote: >> On Sat, Jul 15, 2017 at 12:06 AM, Marek Vasut marex@denx.de wrote: >>> On 07/14/2017 11:46 PM, Benoît Thébaudeau wrote: >>>> On Fri, Jul 14, 2017 at 1:50 PM, Marek Vasut marex@denx.de wrote: >>>>> On 07/14/2017 01:03 PM, Masahiro Yamada wrote: >>>>>> 2017-07-14 19:07 GMT+09:00 Marek Vasut marex@denx.de: >>>>>>> On 07/14/2017 04:31 AM, Masahiro Yamada wrote: >>>>>>>> Prior to DM, we could not enable different types of USB controllers >>>>>>>> at the same time. DM was supposed to loosen the limitation. It is >>>>>>>> true that we can compile drivers, but they do not work. >>>>>>>> >>>>>>>> For example, if EHCI is enabled, xHCI fails as follows: >>>>>>>> >>>>>>>> => usb read 82000000 0 2000 >>>>>>>> >>>>>>>> USB read: device 0 block # 0, count 8192 ... WARN halted endpoint, queueing URB anyway. >>>>>>>> Unexpected XHCI event TRB, skipping... (3fb54010 00000001 13000000 01008401) >>>>>>>> BUG: failure at drivers/usb/host/xhci-ring.c:489/abort_td()! >>>>>>>> BUG! >>>>>>>> ### ERROR ### Please RESET the board ### >>>>>>>> >>>>>>>> The cause of the error seems the following code: >>>>>>>> >>>>>>>> #ifdef CONFIG_USB_EHCI_HCD >>>>>>>> /* >>>>>>>> * The U-Boot EHCI driver can handle any transfer length as long as there is >>>>>>>> * enough free heap space left, but the SCSI READ(10) and WRITE(10) commands are >>>>>>>> * limited to 65535 blocks. >>>>>>>> */ >>>>>>>> #define USB_MAX_XFER_BLK 65535 >>>>>>>> #else >>>>>>>> #define USB_MAX_XFER_BLK 20 >>>>>>>> #endif >>>>>>>> >>>>>>>> To fix the problem, choose the chunk size at run-time for CONFIG_BLK. >>>>>>> >>>>>>> What happens if CONFIG_BLK is not set ? >>>>>> >>>>>> USB_MAX_XFER_BLK is chosen. >>>>> >>>>> And can we fix that even for non-CONFIG_BLK ? >>>>> >>>>>>> Why is it 20 for XHCI anyway ? >>>>>> >>>>>> You are the maintainer. >>>>>> (I hope) you have better knowledge with this. >>>>> >>>>> Heh, way to deflect the question. I seem to remember some discussion >>>>> about the DMA (?) limitation on XHCI, but I'd have to dig through the ML >>>>> archives myself. >>>>> >>>>>> Looks like the following commit was picked up by you. >>>>> >>>>> 5 years ago, way before DM was what it is today . >>>> >>>> And even way before the introduction of XHCI into U-Boot, which means >>>> that this 20 was targeting OHCI or proprietary HCDs, not XHCI. >>>> USB_MAX_READ_BLK was already set to 20 in the initial revision of >>>> usb_storage.c. As I said in the commit message, this 20 was certainly >>>> not optimal for these non-EHCI HCDs, but it restored the previous >>>> (i.e. pre-5dd95cf) behavior for these HCDs instead of using the 5 * 4 >>>> KiB code, which was specific to ehci-hcd.c at that time. Without >>>> knowing the rationale for the legacy 20 blocks, the safest approach >>>> for non-EHCI HCDs was to use this value in order to avoid breaking a >>>> platform or something. Looking at ohci-hcd.c, it limits the transfer >>>> size to (N_URB_TD - 2) * 4 KiB, with N_URB_TD set to 48, so the >>>> maximum number of transfers would depend on the MSC block size. >>>> dwc2.c, isp116x-hcd.c, r8a66597-hcd.c, and sl811-hcd.c do not seem to >>>> have any limit caused by these drivers. The limit with the current >>>> XHCI code seems to be 64 * 64 KiB. So, nowadays, USB_MAX_XFER_BLK >>>> could be set to 65535 for all HCDs but OHCI and XHCI, which require >>>> specific rules depending on the MSC block size. >>> >>> For whatever reason, something tells me that setting the block size to >>> 64k for XHCI broke things, but I cannot locate the thread. But there's >>> something in the back of my head ... >> >> Indeed: according to what I said above, USB_MAX_XFER_BLK cannot be set >> to 65535 for XHCI. With an MSC block size of blksz = 512 bytes / >> block, USB_MAX_XFER_BLK can be set to at most 1 segment * >> (TRBS_PER_SEGMENT = 64 TRBs / segment) * (TRB_MAX_BUFF_SIZE = 65536 >> bytes / TRB) / blksz = 8192 blocks for XHCI. And for OHCI, the limit >> is (N_URB_TD - 2 = 46 TDs) * (4096 bytes / TD) / blksz = 368 blocks. >> The buffer alignment may also have to be taken into account to adjust >> these values, which would require a USB_MAX_XFER_BLK(host_if, start, >> blksz) macro or function. USB_MAX_XFER_BLK can however be set to 65535 >> regardless of blksz for all the other HCDs (i.e. EHCI, dwc2.c, >> isp116x-hcd.c, r8a66597-hcd.c, and sl811-hcd.c). > > That's probably what I was looking for, thanks. >
So, how shall we handle this?
If somebody can fix this in a correct way, I am happy to hand over this.
Any way to fix it for !CONFIG_BLK ?
common/usb_storage.c is sprinkled with ugly #ifdef CONFIG_BLK
IIUC, !CONFIG_BLK code will be removed after migration.
Is it worthwhile to save !CONFIG_BLK case?
Hmmmmmm, sigh. When is the migration happening, how far is it ?
One idea is to force all board to switch to driver model at a preset timeline. After the deadline, boards do not switch to DM will get dropped by the mainline. I noticed that not all boards are actively maintained...
Be my guest, there's a few which I'd like to see removed myself :-)
That makes sense although I'm not sure what the deadline should be. CONFIG_BLK is invasive and it is a pain to carry the #ifdefs.
Maybe end of year, or is that too short?
-- Best regards, Marek Vasut