linux-kernel - Re: [net-next v2] net: wwan: t7xx: PCIe reset rescan

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Message-Id: <20240814113253.5471-1-jinjian.song@fibocom.com>
Date: Wed, 14 Aug 2024 19:32:53 +0800
From: Jinjian Song <jinjian.song@...ocom.com>
To: pabeni@...hat.com,
	Jinjian Song <jinjian.song@...ocom.com>,
	chandrashekar.devegowda@...el.com,
	chiranjeevi.rapolu@...ux.intel.com,
	haijun.liu@...iatek.com,
	m.chetan.kumar@...ux.intel.com,
	ricardo.martinez@...ux.intel.com,
	loic.poulain@...aro.org,
	ryazanov.s.a@...il.com,
	johannes@...solutions.net,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org
Cc: angelogioacchino.delregno@...labora.com,
	corbet@....net,
	danielwinkler@...gle.com,
	helgaas@...nel.org,
	korneld@...gle.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-mediatek@...ts.infradead.org,
	matthias.bgg@...il.com,
	netdev@...r.kernel.org
Subject: Re: [net-next v2] net: wwan: t7xx: PCIe reset rescan

From: Paolo Abeni <pabeni@...hat.com>

>On 8/9/24 05:37, Jinjian Song wrote:
>> WWAN device is programmed to boot in normal mode or fastboot mode,
>> when triggering a device reset through ACPI call or fastboot switch
>> command.Maintain state machine synchronization and reprobe logic
>	^^^      ^^^
>Minor nits: missing space and missing article above.

Please let me modify it.

>> after a device reset.
>> 
>> Suggestion from Bjorn:
>> Link: https://lore.kernel.org/all/20230127133034.GA1364550@bhelgaas/
>> 
>> Signed-off-by: Jinjian Song <jinjian.song@...ocom.com>
>> ---
>> V2:
>>   * initialize the variable 'ret' in t7xx_reset_device() function
>> ---
>>   drivers/net/wwan/t7xx/t7xx_modem_ops.c     | 47 ++++++++++++++++---
>>   drivers/net/wwan/t7xx/t7xx_modem_ops.h     |  9 +++-
>>   drivers/net/wwan/t7xx/t7xx_pci.c           | 53 ++++++++++++++++++----
>>   drivers/net/wwan/t7xx/t7xx_pci.h           |  3 ++
>>   drivers/net/wwan/t7xx/t7xx_port_proxy.c    |  1 -
>>   drivers/net/wwan/t7xx/t7xx_port_trace.c    |  1 +
>>   drivers/net/wwan/t7xx/t7xx_state_monitor.c | 34 +++++---------
>>   7 files changed, 105 insertions(+), 43 deletions(-)
>> 
>> diff --git a/drivers/net/wwan/t7xx/t7xx_modem_ops.c b/drivers/net/wwan/t7xx/t7xx_modem_ops.c
>> index 8d864d4ed77f..79f17100f70b 100644
>> --- a/drivers/net/wwan/t7xx/t7xx_modem_ops.c
>> +++ b/drivers/net/wwan/t7xx/t7xx_modem_ops.c
>> @@ -53,6 +53,7 @@
>>   
>>   #define RGU_RESET_DELAY_MS	10
>>   #define PORT_RESET_DELAY_MS	2000
>> +#define FASTBOOT_RESET_DELAY_MS	2000
>>   #define EX_HS_TIMEOUT_MS	5000
>>   #define EX_HS_POLL_DELAY_MS	10
>>   
>> @@ -167,19 +168,52 @@ static int t7xx_acpi_reset(struct t7xx_pci_dev *t7xx_dev, char *fn_name)
>>   	}
>>   
>>   	kfree(buffer.pointer);
>> +#else
>> +	struct device *dev = &t7xx_dev->pdev->dev;
>> +	int ret;
>>   
>> +	ret = pci_reset_function(t7xx_dev->pdev);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to reset device, error:%d\n", ret);
>> +		return ret;
>> +	}
>>   #endif
>>   	return 0;
>>   }
>>   
>> -int t7xx_acpi_fldr_func(struct t7xx_pci_dev *t7xx_dev)
>> +static void t7xx_host_event_notify(struct t7xx_pci_dev *t7xx_dev, unsigned int event_id)
>>   {
>> -	return t7xx_acpi_reset(t7xx_dev, "_RST");
>> +	u32 value;
>> +
>> +	value = ioread32(IREG_BASE(t7xx_dev) + T7XX_PCIE_MISC_DEV_STATUS);
>> +	value &= ~HOST_EVENT_MASK;
>> +	value |= FIELD_PREP(HOST_EVENT_MASK, event_id);
>> +	iowrite32(value, IREG_BASE(t7xx_dev) + T7XX_PCIE_MISC_DEV_STATUS);
>>   }
>>   
>> -int t7xx_acpi_pldr_func(struct t7xx_pci_dev *t7xx_dev)
>> +int t7xx_reset_device(struct t7xx_pci_dev *t7xx_dev, enum reset_type type)
>>   {
>> -	return t7xx_acpi_reset(t7xx_dev, "MRST._RST");
>> +	int ret = 0;
>> +
>> +	pci_save_state(t7xx_dev->pdev);
>> +	t7xx_pci_reprobe_early(t7xx_dev);
>> +	t7xx_mode_update(t7xx_dev, T7XX_RESET);
>> +
>> +	if (type == FLDR) {
>> +		ret = t7xx_acpi_reset(t7xx_dev, "_RST");
>> +	} else if (type == PLDR) {
>> +		ret = t7xx_acpi_reset(t7xx_dev, "MRST._RST");
>> +	} else if (type == FASTBOOT) {
>> +		t7xx_host_event_notify(t7xx_dev, FASTBOOT_DL_NOTIFY);
>> +		t7xx_mhccif_h2d_swint_trigger(t7xx_dev, H2D_CH_DEVICE_RESET);
>> +		msleep(FASTBOOT_RESET_DELAY_MS);
>
>Did you test this with CONFIG_DEBUG_ATOMIC_SLEEP?
>
>AFAICS the above adds a 2s (FASTBOOT_RESET_DELAY_MS) unconditional sleep 
>for 'fastboot' inside am IRQ thread function via:
>
>t7xx_rgu_isr_thread() -> t7xx_reset_device_via_pmic() -> t7xx_reset_device()
>
>Well, the existing code already looks broken with a 10 ms sleep there, 
>still...

I have not test this with CONFIG_DEBUG_ATOMIC_SLEEP, The FATBOOT reset don't use
during IRQ thread, it only used by sysfs attribute interface, so I think we don't
have to worry about this.

Device IRQ -> t7xx_rgu_isr_thread()->t7xx_reset_device_via_pmic()-> only support FLDR and PLDR reset as before.
sysfs attribute 't7xx_mode' -> t7xx_reset_device(FASTBOOT), this way will use FASTBOOT reset.

>> diff --git a/drivers/net/wwan/t7xx/t7xx_pci.c b/drivers/net/wwan/t7xx/t7xx_pci.c
>> index 10a8c1080b10..2398f41046ce 100644
>> --- a/drivers/net/wwan/t7xx/t7xx_pci.c
>> +++ b/drivers/net/wwan/t7xx/t7xx_pci.c
>> @@ -67,6 +67,7 @@ static ssize_t t7xx_mode_store(struct device *dev,
>>   			       struct device_attribute *attr,
>>   			       const char *buf, size_t count)
>>   {
>> +	enum t7xx_mode mode;
>>   	struct t7xx_pci_dev *t7xx_dev;
>>   	struct pci_dev *pdev;
>>   	int index = 0;
>
>Minor nit: please respect the reverse xmas tree above.
>

Please let me modify it.

Thanks,

Best Regards,
Jinjian