linux-kernel - Re: [PATCH V6 01/21] irqchip: tegra: Do not disable COP IRQ during suspend

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Date:   Mon, 22 Jul 2019 11:13:16 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Dmitry Osipenko <digetx@...il.com>,
        Sowjanya Komatineni <skomatineni@...dia.com>,
        thierry.reding@...il.com, jonathanh@...dia.com, tglx@...utronix.de,
        jason@...edaemon.net, linus.walleij@...aro.org, stefan@...er.ch,
        mark.rutland@....com
Cc:     pdeschrijver@...dia.com, pgaikwad@...dia.com, sboyd@...nel.org,
        linux-clk@...r.kernel.org, linux-gpio@...r.kernel.org,
        jckuo@...dia.com, josephl@...dia.com, talho@...dia.com,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        mperttunen@...dia.com, spatra@...dia.com, robh+dt@...nel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH V6 01/21] irqchip: tegra: Do not disable COP IRQ during
 suspend

On 22/07/2019 10:54, Dmitry Osipenko wrote:
> 21.07.2019 22:40, Sowjanya Komatineni пишет:
>> Tegra210 platforms use sc7 entry firmware to program Tegra LP0/SC7 entry
>> sequence and sc7 entry firmware is run from COP/BPMP-Lite.
>>
>> So, COP/BPMP-Lite still need IRQ function to finish SC7 suspend sequence
>> for Tegra210.
>>
>> This patch has fix for leaving the COP IRQ enabled for Tegra210 during
>> interrupt controller suspend operation.
>>
>> Acked-by: Thierry Reding <treding@...dia.com>
>> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
>> ---
>>  drivers/irqchip/irq-tegra.c | 20 ++++++++++++++++++--
>>  1 file changed, 18 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/irqchip/irq-tegra.c b/drivers/irqchip/irq-tegra.c
>> index e1f771c72fc4..851f88cef508 100644
>> --- a/drivers/irqchip/irq-tegra.c
>> +++ b/drivers/irqchip/irq-tegra.c
>> @@ -44,6 +44,7 @@ static unsigned int num_ictlrs;
>>  
>>  struct tegra_ictlr_soc {
>>  	unsigned int num_ictlrs;
>> +	bool supports_sc7;
>>  };
>>  
>>  static const struct tegra_ictlr_soc tegra20_ictlr_soc = {
>> @@ -56,6 +57,7 @@ static const struct tegra_ictlr_soc tegra30_ictlr_soc = {
>>  
>>  static const struct tegra_ictlr_soc tegra210_ictlr_soc = {
>>  	.num_ictlrs = 6,
>> +	.supports_sc7 = true,
>>  };
>>  
>>  static const struct of_device_id ictlr_matches[] = {
>> @@ -67,6 +69,7 @@ static const struct of_device_id ictlr_matches[] = {
>>  
>>  struct tegra_ictlr_info {
>>  	void __iomem *base[TEGRA_MAX_NUM_ICTLRS];
>> +	const struct tegra_ictlr_soc *soc;
>>  #ifdef CONFIG_PM_SLEEP
>>  	u32 cop_ier[TEGRA_MAX_NUM_ICTLRS];
>>  	u32 cop_iep[TEGRA_MAX_NUM_ICTLRS];
>> @@ -147,8 +150,20 @@ static int tegra_ictlr_suspend(void)
>>  		lic->cop_ier[i] = readl_relaxed(ictlr + ICTLR_COP_IER);
>>  		lic->cop_iep[i] = readl_relaxed(ictlr + ICTLR_COP_IEP_CLASS);
>>  
>> -		/* Disable COP interrupts */
>> -		writel_relaxed(~0ul, ictlr + ICTLR_COP_IER_CLR);
>> +		/*
>> +		 * AVP/COP/BPMP-Lite is the Tegra boot processor.
>> +		 *
>> +		 * Tegra210 system suspend flow uses sc7entry firmware which
>> +		 * is executed by COP/BPMP and it includes disabling COP IRQ,
>> +		 * clamping CPU rail, turning off VDD_CPU, and preparing the
>> +		 * system to go to SC7/LP0.
>> +		 *
>> +		 * COP/BPMP wakes up when COP IRQ is triggered and runs
>> +		 * sc7entry-firmware. So need to keep COP interrupt enabled.
>> +		 */
>> +		if (!lic->soc->supports_sc7)
>> +			/* Disable COP interrupts if SC7 is not supported */
> 
> All Tegra SoCs support SC7, hence the 'supports_sc7' and the comment
> doesn't sound correct to me. Something like 'firmware_sc7' should suit
> better here.

If what you're saying is true, then the whole patch is wrong, and the
SC7 property should come from DT.

> 
>> +			writel_relaxed(~0ul, ictlr + ICTLR_COP_IER_CLR);
> 
> Secondly, I'm also not sure why COP interrupts need to be disabled for
> pre-T210 at all, since COP is unused. This looks to me like it was
> cut-n-pasted from downstream kernel without a good reason and could be
> simply removed.

Please verify that this is actually the case. Tegra-2 definitely needed
some level of poking, and I'm not keen on changing anything there until
you (or someone else) has verified it on actual HW (see e307cc8941fc).

Joseph, can you please shed some light here?

	M.
-- 
Jazz is not dead. It just smells funny...