Subject: Re: [PATCH] ath10k: reset chip after supported check
From:   Arend Van Spriel <arend.vanspriel@broadcom.com>
To:     Christian Lamparter <chunkeey@gmail.com>,
        =?UTF-8?Q?Tomislav_Po=c5=beega?= <pozega.tomislav@gmail.com>
Cc:     linux-wireless <linux-wireless@vger.kernel.org>,
        openwrt-devel@lists.openwrt.org, Kalle Valo <kvalo@codeaurora.org>,
        =?UTF-8?Q?Micha=c5=82_Kazior?= <kazikcz@gmail.com>
References: <1553281120-22139-1-git-send-email-pozega.tomislav@gmail.com>
 <3337086.qEUs9xMCTV@debian64>
 <fe853ec8-0dca-d931-8632-fbe4df5cfaf8@broadcom.com>
Message-ID: <edc38f32-977a-53f5-babd-605775326a20@broadcom.com>
Date:   Sat, 23 Mar 2019 08:20:07 +0100
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* resending with corrected email address from Kalle
--------------------------------------------------------------------
+ Michał

On 3/22/2019 8:25 PM, Christian Lamparter wrote:
 > On Friday, March 22, 2019 7:58:40 PM CET Tomislav Požega wrote:
 >> When chip reset is done before the chip is checked if supported
 >> there will be crash. Previous behaviour caused bootloops on
 >> Archer C7 v1 units, this patch allows clean device boot without
 >> excluding ath10k driver.
 >>
 > You need
 >
 > Fixes: 1a7fecb766c8 ("ath10k: reset chip before reading chip_id in 
probe")
 >
 > too

Looking at the commit subject makes me suspicious whether this is a 
proper fix.

 >> Signed-off-by: Tomislav Požega <pozega.tomislav@gmail.com>
 >> ---
 >>   drivers/net/wireless/ath/ath10k/pci.c |   12 ++++++------
 >>   1 files changed, 6 insertions(+), 6 deletions(-)
 >>
 >> diff --git a/drivers/net/wireless/ath/ath10k/pci.c 
b/drivers/net/wireless/ath/ath10k/pci.c
 >> index e24403c..ec681da 100644
 >> --- a/drivers/net/wireless/ath/ath10k/pci.c
 >> +++ b/drivers/net/wireless/ath/ath10k/pci.c
 >> @@ -3619,12 +3619,6 @@ static int ath10k_pci_probe(struct pci_dev *pdev,
 >>   		goto err_deinit_irq;
 >>   	}
 >>
 >> -	ret = ath10k_pci_chip_reset(ar);
 >> -	if (ret) {
 >> -		ath10k_err(ar, "failed to reset chip: %d\n", ret);
 >> -		goto err_free_irq;
 >> -	}
 >> -
 >>   	bus_params.dev_type = ATH10K_DEV_TYPE_LL;
 >>   	bus_params.link_can_suspend = true;
 >>   	bus_params.chip_id = ath10k_pci_soc_read32(ar, SOC_CHIP_ID_ADDRESS);

It seems to me the chip reset was done explicitly *before* reading the 
chipid for a reason.

"""
ath10k: reset chip before reading chip_id in probe
There are some very rare cases with some hardware
configuration that the device doesn't init quickly
enough in which case reading chip_id yielded 0.
This caused driver to subsequently fail to setup
the device.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
"""

Might be the ath10k_pci_chip_reset() function needs to be modified to 
work properly for Archer C7 v1 units.

Regards,
Arend