linux-kernel - Re: [PATCH] thunderbolt: Clear registers properly when auto clear isn't in use

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Message-ID: <9912a4ce-a819-9289-02be-71546161e95b@amd.com>
Date:   Mon, 24 Apr 2023 08:30:05 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     Andreas Noever <andreas.noever@...il.com>,
        Michael Jamet <michael.jamet@...el.com>,
        Yehezkel Bernat <YehezkelShB@...il.com>,
        S Sanath <Sanath.S@....com>, richard.gong@....com,
        Sanju.Mehta@....com, Takashi Iwai <tiwai@...e.de>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] thunderbolt: Clear registers properly when auto clear
 isn't in use


On 4/24/23 00:58, Mika Westerberg wrote:
> Hi Mario,
>
> On Fri, Apr 21, 2023 at 09:07:24AM -0500, Mario Limonciello wrote:
>> When `QUIRK_AUTO_CLEAR_INT` isn't set, interrupt masking should be
>> cleared by writing to Interrupt Mask Clear (IMR) and interrupt
>> status should be cleared properly at shutdown/init.
>>
>> This fixes an error where interrupts are left enabled during resume
>> from hibernation with `CONFIG_USB4=y`.
>>
>> Fixes: 468c49f44759 ("thunderbolt: Disable interrupt auto clear for rings")
>> Reported-by: Takashi Iwai <tiwai@...e.de>
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=217343
>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>> Tested-by: Takashi Iwai <tiwai@...e.de>
>> ---
>> I tried to base this off thunderbolt.git/next (tag: thunderbolt-for-v6.4-rc1)
>> but the following 3 commits are missing from that branch but are in 6.3-rc7:
>>
>> 58cdfe6f58b3 thunderbolt: Rename shadowed variables bit to interrupt_bit and auto_clear_bit
>> 468c49f44759 thunderbolt: Disable interrupt auto clear for rings
>> 1716efdb0793 thunderbolt: Use const qualifier for `ring_interrupt_index`
>>
>> I cherry picked them first as this patch builds on them.
> Okay, so if I take this after v6.4-rc1 is released and send it forward
> to for -rc2 Greg it should apply just fine?
Yes; that's right.  I'll rework it for your below comments and that plan 
sounds good to me.
>> ---
>>   drivers/thunderbolt/nhi.c      | 28 +++++++++++++++++++++-------
>>   drivers/thunderbolt/nhi_regs.h |  1 +
>>   2 files changed, 22 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
>> index d76e923fbc6a..7c543a6a5711 100644
>> --- a/drivers/thunderbolt/nhi.c
>> +++ b/drivers/thunderbolt/nhi.c
>> @@ -61,8 +61,9 @@ static int ring_interrupt_index(const struct tb_ring *ring)
>>    */
>>   static void ring_interrupt_active(struct tb_ring *ring, bool active)
>>   {
>> -	int reg = REG_RING_INTERRUPT_BASE +
>> -		  ring_interrupt_index(ring) / 32 * 4;
>> +	int index = ring_interrupt_index(ring) / 32 * 4;
>> +	int reg = REG_RING_INTERRUPT_BASE + index;
>> +	int clear = REG_RING_INTERRUPT_MASK_CLEAR_BASE + index;
>>   	int interrupt_bit = ring_interrupt_index(ring) & 31;
>>   	int mask = 1 << interrupt_bit;
>>   	u32 old, new;
>> @@ -123,7 +124,11 @@ static void ring_interrupt_active(struct tb_ring *ring, bool active)
>>   					 "interrupt for %s %d is already %s\n",
>>   					 RING_TYPE(ring), ring->hop,
>>   					 active ? "enabled" : "disabled");
>> -	iowrite32(new, ring->nhi->iobase + reg);
>> +
>> +	if (active)
>> +		iowrite32(new, ring->nhi->iobase + reg);
>> +	else
>> +		iowrite32(mask, ring->nhi->iobase + clear);
> Since it is doing this for all hardware, even for Intel, I will need to
> run some testing to make sure this still works.
OK.
>>   }
>>   
>>   /*
>> @@ -135,12 +140,21 @@ static void nhi_disable_interrupts(struct tb_nhi *nhi)
>>   {
>>   	int i = 0;
>>   	/* disable interrupts */
>> -	for (i = 0; i < RING_INTERRUPT_REG_COUNT(nhi); i++)
>> -		iowrite32(0, nhi->iobase + REG_RING_INTERRUPT_BASE + 4 * i);
>> +	for (i = 0; i < RING_INTERRUPT_REG_COUNT(nhi); i++) {
>> +		if (nhi->quirks & QUIRK_AUTO_CLEAR_INT)
>> +			iowrite32(0, nhi->iobase + REG_RING_INTERRUPT_BASE + 4 * i);
>> +		else
>> +			iowrite32(0xffffffff,
> ~0
>
>> +				  nhi->iobase + REG_RING_INTERRUPT_MASK_CLEAR_BASE + 4 * i);
> Btw, we have now quite many places with
>
> 	if (nhi->quirks & QUIRK_AUTO_CLEAR_INT)
> 		// Intel stuff
> 	else
> 		// non-Intel stuff
>
> I wonder if we could move these behind a wrapper and then here (and
> similar places) just call
>
> 	nhi_mask_interrupt(nhi, ...)

Sure, I'll experiment with this, it does sound like a generally good 
improvement for the code.

>
>> +	}
>>   
>>   	/* clear interrupt status bits */
>> -	for (i = 0; i < RING_NOTIFY_REG_COUNT(nhi); i++)
>> -		ioread32(nhi->iobase + REG_RING_NOTIFY_BASE + 4 * i);
>> +	for (i = 0; i < RING_NOTIFY_REG_COUNT(nhi); i++) {
>> +		if (nhi->quirks & QUIRK_AUTO_CLEAR_INT)
>> +			ioread32(nhi->iobase + REG_RING_NOTIFY_BASE + 4 * i);
>> +		else
>> +			iowrite32(0xffffffff, nhi->iobase + REG_RING_INT_CLEAR + 4 * i);
> ~0
>
> 	nhi_clear_interrupt(nhi, ...)
>
>> +	}
>>   }
>>   
>>   /* ring helper methods */
>> diff --git a/drivers/thunderbolt/nhi_regs.h b/drivers/thunderbolt/nhi_regs.h
>> index faef165a919c..db95ad5d2814 100644
>> --- a/drivers/thunderbolt/nhi_regs.h
>> +++ b/drivers/thunderbolt/nhi_regs.h
>> @@ -92,6 +92,7 @@ struct ring_desc {
>>    */
>>   #define REG_RING_INTERRUPT_BASE	0x38200
>>   #define RING_INTERRUPT_REG_COUNT(nhi) ((31 + 2 * nhi->hop_count) / 32)
> Empty line here.
>
>> +#define REG_RING_INTERRUPT_MASK_CLEAR_BASE	0x38208
>>   
>>   #define REG_INT_THROTTLING_RATE	0x38c00
>>   
>> -- 
>> 2.34.1