From bcbddc4f9d020a4a0b881cc065729c3aaeb28098 Mon Sep 17 00:00:00 2001 From: Emmanuel Grumbach Date: Mon, 20 Dec 2021 14:33:18 +0200 Subject: iwlwifi: mei: wait before mapping the shared area The shared area is a DMA memory allocated in the host and mapped so that the host and the CSME firmware can exchange data. It is mapped through a dedicated PCI device that is driven by the mei bus driver. The bus driver is in charge of allocating and mapping this memory. It also needs to configure the CSME firmware with a specific set of commands, so that the CSME firmware will know that this memory is meant to be used by its internal WLAN module. For this, the CSME firmware first needs to completely initialize its WLAN module and only then get the mapping request. The problem is that the mei bus enumeration completes before the WLAN is completely ready. This means that the WLAN module's initialization is racing with iwlmei's allocation and mapping flow. Testing showed a problem in resume flows where iwlmei was too fast and the DMA mapping failed. Add a delay to avoid this. This is still racy, but our measurements showed that we have a good margin and we should now be safe. Fixes: 2da4366f9e2c ("iwlwifi: mei: add the driver to allow cooperation with CSME") Signed-off-by: Emmanuel Grumbach Signed-off-by: Luca Coelho Link: https://lore.kernel.org/r/iwlwifi.20211220142940.8b6279e3d0be.I6fe128b0b86149a85535104822c8355b367887c8@changeid Signed-off-by: Luca Coelho --- drivers/net/wireless/intel/iwlwifi/mei/main.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'drivers/net/wireless') diff --git a/drivers/net/wireless/intel/iwlwifi/mei/main.c b/drivers/net/wireless/intel/iwlwifi/mei/main.c index 787d64276f36..bee3415ef460 100644 --- a/drivers/net/wireless/intel/iwlwifi/mei/main.c +++ b/drivers/net/wireless/intel/iwlwifi/mei/main.c @@ -1810,6 +1810,12 @@ static int iwl_mei_probe(struct mei_cl_device *cldev, mei_cldev_set_drvdata(cldev, mei); mei->cldev = cldev; + /* + * The CSME firmware needs to boot the internal WLAN client. Wait here + * so that the DMA map request will succeed. + */ + msleep(20); + ret = iwl_mei_alloc_shared_mem(cldev); if (ret) goto free; -- cgit v1.2.3-59-g8ed1b