| Message ID | 20210717204057.67495-1-martin.blumenstingl@googlemail.com |
|---|---|
| Headers | show |
| Series | rtw88: prepare locking for SDIO support | expand |
> -----Original Message----- > From: Martin Blumenstingl [mailto:martin.blumenstingl@googlemail.com] > Sent: Sunday, July 18, 2021 4:41 AM > To: linux-wireless@vger.kernel.org > Cc: tony0620emma@gmail.com; kvalo@codeaurora.org; johannes@sipsolutions.net; netdev@vger.kernel.org; > linux-kernel@vger.kernel.org; Neo Jou; Jernej Skrabec; Martin Blumenstingl > Subject: [PATCH RFC v1 0/7] rtw88: prepare locking for SDIO support > [...] I have reviewed patchset v1. But, please wait a moment before sending v2 to see if other experts have better suggestions. -- Ping-Ke
Hello rtw88 and mac80211 maintainers/contributors, there is an ongoing effort where Jernej and I are working on adding SDIO support to the rtw88 driver. The hardware we use at the moment is RTL8822BS and RTL8822CS. We are at a point where scanning, assoc etc. works (though it's not fast yet, in my tests I got ~6Mbit/s in either direction). This series contains some preparation work for adding SDIO support. While testing our changes we found that there are some "scheduling while atomic" errors in the kernel log. These are due to the fact that the SDIO accessors (sdio_readb, sdio_writeb and friends) may sleep internally. Some background on why SDIO access (for example: sdio_writeb) cannot be done with a spinlock held (this is a copy from my previous mail, see [0]): - when using for example sdio_writeb the MMC subsystem in Linux prepares a so-called MMC request - this request is submitted to the MMC host controller hardware - the host controller hardware forwards the MMC request to the card - the card signals when it's done processing the request - the MMC subsystem in Linux waits for the card to signal that it's done processing the request in mmc_wait_for_req_done() -> this uses wait_for_completion() internally, which might sleep (which is not allowed while a spinlock is held) Based on Ping-Ke's suggestion I came up with the code in this series. The goal is to use non-atomic locking for all register access in the rtw88 driver. One patch adds a new function to mac80211 which did not have a "non-atomic" version of it's "atomic" counterpart yet. As mentioned before I don't have any rtw88 PCIe device so I am unable to test on that hardware. I am sending this as an RFC series since I am new to the mac80211 subsystem as well as the rtw88 driver. So any kind of feedback is very welcome! The actual changes for adding SDIO support will be sent separately in the future. [0] https://lore.kernel.org/linux-wireless/CAFBinCDMPPJ7qW7xTkep1Trg+zP0B9Jxei6sgjqmF4NDA1JAhQ@mail.gmail.com/ Martin Blumenstingl (7): mac80211: Add stations iterator where the iterator function may sleep rtw88: Use rtw_iterate_vifs where the iterator reads or writes registers rtw88: Use rtw_iterate_stas where the iterator reads or writes registers rtw88: Replace usage of rtw_iterate_keys_rcu() with rtw_iterate_keys() rtw88: Configure the registers from rtw_bf_assoc() outside the RCU lock rtw88: hci: Convert rf_lock from a spinlock to a mutex rtw88: fw: Convert h2c.lock from a spinlock to a mutex drivers/net/wireless/realtek/rtw88/bf.c | 8 ++++++-- drivers/net/wireless/realtek/rtw88/fw.c | 14 +++++++------- drivers/net/wireless/realtek/rtw88/hci.h | 11 ++++------- drivers/net/wireless/realtek/rtw88/mac80211.c | 2 +- drivers/net/wireless/realtek/rtw88/main.c | 16 +++++++--------- drivers/net/wireless/realtek/rtw88/main.h | 4 ++-- drivers/net/wireless/realtek/rtw88/phy.c | 4 ++-- drivers/net/wireless/realtek/rtw88/ps.c | 2 +- drivers/net/wireless/realtek/rtw88/util.h | 4 ++-- drivers/net/wireless/realtek/rtw88/wow.c | 2 +- include/net/mac80211.h | 18 ++++++++++++++++++ net/mac80211/util.c | 13 +++++++++++++ 12 files changed, 64 insertions(+), 34 deletions(-)