Date: Thu, 28 Dec 2017 11:28:47 +0200 From: "Andriy Voskoboinyk" <s3erios@gmail.com> To: "Farhan Khan" <khanzf@gmail.com> Cc: freebsd-wireless@freebsd.org Subject: Re: rtwn(4) extension rtl8188ee receiving constantly interrupts Message-ID: <op.zbx9x9ktiew4ia@localhost> In-Reply-To: <CA%2BRfiRFA8YBTB0tfJSxb9UUqUKGeUWb720EqKX-GFHTqeWT1Pg@mail.gmail.com> References: <CAFd4kYD_McuQC3=vwo9RxJfXkVn=NmLWKCj5r%2BhQaEUmWMRv2w@mail.gmail.com> <CA%2BRfiRFA8YBTB0tfJSxb9UUqUKGeUWb720EqKX-GFHTqeWT1Pg@mail.gmail.com>
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Hi, there are some issues that may cause wrong interrupt handling: 1) IMR register bits - they were taken from 92c (and they are not compatible - for example, RXFOVW seems to be moved to the ext register) 2) Try to ACK (write back) all bits, not masked ones (like it is done for 92c) 2017-12-22 0:43 GMT+02:00, Farhan Khan <khanzf@gmail.com>: >> 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-unsubscribe@freebsd.org"
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