netdev - Re: [PATCH 3/3] can: flexcan: handle S32G2/S32G3 separate interrupt lines

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Message-ID: <57915ed9-e57e-4ca3-bc31-6405893c937e@wanadoo.fr>
Date: Tue, 19 Nov 2024 18:26:51 +0900
From: Vincent Mailhol <mailhol.vincent@...adoo.fr>
To: Ciprian Costea <ciprianmarian.costea@....nxp.com>,
 Marc Kleine-Budde <mkl@...gutronix.de>, Andrew Lunn <andrew+netdev@...n.ch>,
 "David S . Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
Cc: linux-can@...r.kernel.org, netdev@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 imx@...ts.linux.dev, NXP Linux Team <s32@....com>,
 Christophe Lizzi <clizzi@...hat.com>, Alberto Ruiz <aruizrui@...hat.com>,
 Enric Balletbo <eballetb@...hat.com>
Subject: Re: [PATCH 3/3] can: flexcan: handle S32G2/S32G3 separate interrupt
 lines

On 19/11/2024 at 17:10, Ciprian Costea wrote:
> From: Ciprian Marian Costea <ciprianmarian.costea@....nxp.com>
> 
> On S32G2/S32G3 SoC, there are separate interrupts
> for state change, bus errors, MBs 0-7 and MBs 8-127 respectively.
> 
> In order to handle this FlexCAN hardware particularity, reuse
> the 'FLEXCAN_QUIRK_NR_IRQ_3' quirk provided by mcf5441x's irq
> handling support.
> 
> Additionally, introduce 'FLEXCAN_QUIRK_SECONDARY_MB_IRQ' quirk,
> which can be used in case there are two separate mailbox ranges
> controlled by independent hardware interrupt lines, as it is
> the case on S32G2/S32G3 SoC.
> 
> Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@....nxp.com>
> ---
>  drivers/net/can/flexcan/flexcan-core.c | 25 +++++++++++++++++++++++--
>  drivers/net/can/flexcan/flexcan.h      |  3 +++
>  2 files changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/can/flexcan/flexcan-core.c b/drivers/net/can/flexcan/flexcan-core.c
> index f0dee04800d3..dc56d4a7d30b 100644
> --- a/drivers/net/can/flexcan/flexcan-core.c
> +++ b/drivers/net/can/flexcan/flexcan-core.c
> @@ -390,9 +390,10 @@ static const struct flexcan_devtype_data nxp_s32g2_devtype_data = {
>  	.quirks = FLEXCAN_QUIRK_DISABLE_RXFG | FLEXCAN_QUIRK_ENABLE_EACEN_RRS |
>  		FLEXCAN_QUIRK_DISABLE_MECR | FLEXCAN_QUIRK_BROKEN_PERR_STATE |
>  		FLEXCAN_QUIRK_USE_RX_MAILBOX | FLEXCAN_QUIRK_SUPPORT_FD |
> -		FLEXCAN_QUIRK_SUPPORT_ECC |
> +		FLEXCAN_QUIRK_SUPPORT_ECC | FLEXCAN_QUIRK_NR_IRQ_3 |
>  		FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX |
> -		FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX_RTR,
> +		FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX_RTR |
> +		FLEXCAN_QUIRK_SECONDARY_MB_IRQ,
>  };
>  
>  static const struct can_bittiming_const flexcan_bittiming_const = {
> @@ -1771,12 +1772,21 @@ static int flexcan_open(struct net_device *dev)
>  			goto out_free_irq_boff;
>  	}
>  
> +	if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SECONDARY_MB_IRQ) {
> +		err = request_irq(priv->irq_secondary_mb,
> +				  flexcan_irq, IRQF_SHARED, dev->name, dev);
> +		if (err)
> +			goto out_free_irq_err;
> +	}

Is the logic here correct?

  request_irq(priv->irq_err, flexcan_irq, IRQF_SHARED, dev->name, dev);

is called only if the device has the FLEXCAN_QUIRK_NR_IRQ_3 quirk.

So, if the device has the FLEXCAN_QUIRK_SECONDARY_MB_IRQ but not the
FLEXCAN_QUIRK_NR_IRQ_3, you may end up trying to free an irq which was
not initialized.

Did you confirm if it is safe to call free_irq() on an uninitialized irq?

(and I can see that currently there is no such device with
FLEXCAN_QUIRK_SECONDARY_MB_IRQ but without FLEXCAN_QUIRK_NR_IRQ_3, but
who knows if such device will be introduced in the future?)

>  	flexcan_chip_interrupts_enable(dev);
>  
>  	netif_start_queue(dev);
>  
>  	return 0;
>  
> + out_free_irq_err:
> +	free_irq(priv->irq_err, dev);
>   out_free_irq_boff:
>  	free_irq(priv->irq_boff, dev);
>   out_free_irq:
> @@ -1808,6 +1818,9 @@ static int flexcan_close(struct net_device *dev)
>  		free_irq(priv->irq_boff, dev);
>  	}
>  
> +	if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SECONDARY_MB_IRQ)
> +		free_irq(priv->irq_secondary_mb, dev);
> +
>  	free_irq(dev->irq, dev);
>  	can_rx_offload_disable(&priv->offload);
>  	flexcan_chip_stop_disable_on_error(dev);
> @@ -2197,6 +2210,14 @@ static int flexcan_probe(struct platform_device *pdev)
>  		}
>  	}
>  
> +	if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SECONDARY_MB_IRQ) {
> +		priv->irq_secondary_mb = platform_get_irq(pdev, 3);
> +		if (priv->irq_secondary_mb < 0) {
> +			err = priv->irq_secondary_mb;
> +			goto failed_platform_get_irq;
> +		}
> +	}
> +
>  	if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SUPPORT_FD) {
>  		priv->can.ctrlmode_supported |= CAN_CTRLMODE_FD |
>  			CAN_CTRLMODE_FD_NON_ISO;
> diff --git a/drivers/net/can/flexcan/flexcan.h b/drivers/net/can/flexcan/flexcan.h
> index 4933d8c7439e..d4b1a954c538 100644
> --- a/drivers/net/can/flexcan/flexcan.h
> +++ b/drivers/net/can/flexcan/flexcan.h
> @@ -70,6 +70,8 @@
>  #define FLEXCAN_QUIRK_SUPPORT_RX_FIFO BIT(16)
>  /* Setup stop mode with ATF SCMI protocol to support wakeup */
>  #define FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI BIT(17)
> +/* Setup secondary mailbox interrupt */
> +#define FLEXCAN_QUIRK_SECONDARY_MB_IRQ	BIT(18)
>  
>  struct flexcan_devtype_data {
>  	u32 quirks;		/* quirks needed for different IP cores */
> @@ -105,6 +107,7 @@ struct flexcan_priv {
>  	struct regulator *reg_xceiver;
>  	struct flexcan_stop_mode stm;
>  
> +	int irq_secondary_mb;
>  	int irq_boff;
>  	int irq_err;
>  

Yours sincerely,
Vincent Mailhol