Hi, So it looks like the thing that's generating the interrupt isn't being cleared.
So, what do the bits in R88EE_HIMR mean? What about HIRME? Let's figure out which it is. Also, is it something in C2H (the target to host event channel) that's not being handled? -adrian On 21 December 2017 at 14:43, Farhan Khan <kha...@gmail.com> wrote: > Hi, > > As I wrote a few weeks back, I am working on the extension to rtwn(4) to add > RTL8188EE support. At the moment, I am working on the Rx code, which handles > interrupts. After the interrupt is triggered, the code goes into the Rx > routine > and delivers "junk data" in a continuous loop. It seems that the interrupt > code > is **constantly** called - enough that the load average is frequently above > 1.0. > > I suspect the issue is giving the WiFi driver an acknowledgement of some sort, > but I am not certain. I attempted to copy Linux's interrupt code as best as > possible, but cannot determine if the error is within my code. > > Here is a verbose explanation of what I believe Linux is doing and what I am > doing on FreeBSD. > > -----Linux code works as follows----- > > 1. The IRQ trigger calls the function _rtl_pci_interrupt > (drivers/net/wireless/realtek/rtlwifi/pci.c) > 2. This calls disable_interrupt, which for rtl8188ee is > rtl88ee_disable_interrupt. This function writes IMR_DISABLED (0x0) to > REG_HIMR (0xb0) and REG_HIMRE (0xb8). > 3. Next _rtl_pci_interrupt calls interrupt_recognized(), a function pointer to > rtl88ee_interrupt_recognized(), which: > * Reads from REG_HISR (0xb4), stores the value in 'inta', ANDs that value > by > 0x200084ff, then writes that value back to the same register. > * Reads from REG_HISRE (0xbc), stores the value in 'intb', ANDs that value > by > 0x100, then writes that value back to the same register. > Then the function returns returns. > > 4. Back in _rtl_pci_interrupt if 'inta' is 0 and 'intb' is 0xffff, the code > will > skip step 5, goto to "done" and execute enable_interrupt code > (rtl88ee_enable_interrupt) > > 5. If bit(0) is set to 1, this is an Rx interrupt and will run > _rtl_pci_rx_interrupt(). From my review of the code, from here the Linux > driver will read from the DMA memory and send the frame to the ieee80211 > layer. I only found 1 additional read instruction related to the power > value, > but nothing else is changed. > > 6. Here is the "done" portion, that happens no matter what, but is jumped to > immediately as referenced above. It will call enable_interrupt(), a > function > pointer to rtl88ee_enable_Interrupt(), which will: > a. Write 0x200084ff to REG_HIMR (0xb0) > b. Write 0x100 to REG_HIMRE (0xb8) > c. Write 0 to to REG_C2HEVT_CLEAR (0x01AF, A register having to do with C2H > firmware) > d. Write 0xc0 to REG_HSIMR (0x58 , I know this value from printf'ing it) > > This is what I identified from reviewing from the Linux code. > > -----My FreeBSD Code----- > > My code is located here: > https://github.com/khanzf/freebsd/tree/rx_not_working/sys/dev/rtwn/. > > 1. The IRQ trigger calls the function rtwn_pci_intr() > (sys/dev/rtwn/pci/rtwn_pci_rx.c) > 2. The equivalent of Linux's line 2 and 3 is in rtwn_classify_intr, which is a > pointer to r88ee_enable_intr located in sys/dev/rtwn/rtl8188e/pci/r88ee_rx. > This write's 0x0 to REG_HIMR (0xb0) and REG_HIMRE (0xb8) > 3. Continuing, the same function: > * Reads from ISR_MINE (same as REG_HISR, 0xb4), ANDs the value by > 0x200084ff, > store it in 'status'. Then I write the value back to the same register. > * Read from REG_HISRE (0xbc), AND the value by 0x100, store it in > 'statusb'. > Write this value back to the same register. > * Since this is an Rx register, the 'ret' value is AND'd by > RTWN_PCI_INTR_RX. > > 4. In the Linux code, if 'status' is 0x0 and 'statusb' is 0xFFFF, it will goto > to "done". On FreeBSD, it simply does not set any bits on the 'ret' value > and > the function returns 0, going back to rtwn_pci_intr. > > 5. Returning to rtwn_pci_intr(), if the 'ret' (now 'status') has > RTWN_PCI_INTR_RX flag on, it executes rtwn_pci_tx_done(), which will read > the > DMA memory and send the frame to the ieee80211 layer. The execution will > skip > step 5 if 'ret' was 0 (the RTWN_PCI_INTR_RX flag was never set). This > returns > execution back to rtwn_pci_intr(). > > 6. rtwn_pci_intr() concludes by running rtwn_pci_enable_intr(). This is > similar > to Linux's enable_interrupt(), it does the following: > a. Write 0x200084f to R88EE_HIMR (0xb0) > b. Write 0x100 to R88EE_HIMRE (0xb8) > c. Write 0x0 to REG_C2HEVT_CLEAR (0x01AF) > d. Write 0xc0 to REG_HSIMR > > --------- > > To me, it appears that I did a complete 1-to-1 copy of the Linux code. > However, > in my case the driver is receiving constant interrupts without stopping. I am > not certain what I am missing or what is different. Could it be that something > outside of this particular code path was not properly set. If so, what might > that be? > > Please advise. > Thank you, > > -- > Farhan Khan > PGP Fingerprint: B28D 2726 E2BC A97E 3854 5ABE 9A9F 00BC D525 16EE > _______________________________________________ > freebsd-wireless@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-wireless > To unsubscribe, send any mail to "freebsd-wireless-unsubscr...@freebsd.org" _______________________________________________ freebsd-wireless@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-wireless To unsubscribe, send any mail to "freebsd-wireless-unsubscr...@freebsd.org"
