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Date: Wed, 30 Dec 2020 09:42:09 +0000
From: Marc Zyngier <maz@...nel.org>
To: DENG Qingfang <dqfext@...il.com>
Cc: "David S. Miller" <davem@...emloft.net>,
Andrew Lunn <andrew@...n.ch>,
Florian Fainelli <f.fainelli@...il.com>,
Heiner Kallweit <hkallweit1@...il.com>,
Jakub Kicinski <kuba@...nel.org>,
Landen Chao <Landen.Chao@...iatek.com>,
Matthias Brugger <matthias.bgg@...il.com>,
Philipp Zabel <p.zabel@...gutronix.de>,
Russell King <linux@...linux.org.uk>,
Sean Wang <sean.wang@...iatek.com>,
Thomas Gleixner <tglx@...utronix.de>,
Vivien Didelot <vivien.didelot@...il.com>,
Vladimir Oltean <olteanv@...il.com>,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
Weijie Gao <weijie.gao@...iatek.com>,
Chuanhong Guo <gch981213@...il.com>,
Linus Walleij <linus.walleij@...aro.org>,
René van Dorst <opensource@...rst.com>
Subject: Re: Registering IRQ for MT7530 internal PHYs
Hi Qingfang,
On 2020-12-30 04:22, DENG Qingfang wrote:
> Hi,
>
> I added MT7530 IRQ support and registered its internal PHYs to IRQ.
> It works but my patch used two hacks.
>
> 1. Removed phy_drv_supports_irq check, because config_intr and
> handle_interrupt are not set for Generic PHY.
>
> 2. Allocated ds->slave_mii_bus before calling ds->ops->setup, because
> we cannot call dsa_slave_mii_bus_init which is private.
>
> Any better ideas?
>
> Regards,
> Qingfang
>
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index a67cac15a724..d59a8c50ede3 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -10,6 +10,7 @@
> #include <linux/mfd/syscon.h>
> #include <linux/module.h>
> #include <linux/netdevice.h>
> +#include <linux/of_irq.h>
> #include <linux/of_mdio.h>
> #include <linux/of_net.h>
> #include <linux/of_platform.h>
> @@ -1639,6 +1640,125 @@ mtk_get_tag_protocol(struct dsa_switch *ds, int
> port,
> }
> }
>
> +static irqreturn_t
> +mt7530_irq(int irq, void *data)
> +{
> + struct mt7530_priv *priv = data;
> + bool handled = false;
> + int phy;
> + u32 val;
> +
> + val = mt7530_read(priv, MT7530_SYS_INT_STS);
> + mt7530_write(priv, MT7530_SYS_INT_STS, val);
If that is an ack operation, it should be dealt with as such in
an irqchip callback instead of being open-coded here.
> +
> + dev_info_ratelimited(priv->dev, "interrupt status: 0x%08x\n", val);
> + dev_info_ratelimited(priv->dev, "interrupt enable: 0x%08x\n",
> mt7530_read(priv, MT7530_SYS_INT_EN));
> +
I don't think printing these from an interrupt handler is a good idea.
Use the debug primitives if you really want these messages.
> + for (phy = 0; phy < MT7530_NUM_PHYS; phy++) {
> + if (val & BIT(phy)) {
> + unsigned int child_irq;
> +
> + child_irq = irq_find_mapping(priv->irq_domain, phy);
> + handle_nested_irq(child_irq);
> + handled = true;
> + }
> + }
> +
> + return handled ? IRQ_HANDLED : IRQ_NONE;
> +}
What is the reason for not implementing this as a chained interrupt
flow?
> +
> +static void mt7530_irq_mask(struct irq_data *d)
> +{
> + struct mt7530_priv *priv = irq_data_get_irq_chip_data(d);
> +
> + priv->irq_enable &= ~BIT(d->hwirq);
> +}
> +
> +static void mt7530_irq_unmask(struct irq_data *d)
> +{
> + struct mt7530_priv *priv = irq_data_get_irq_chip_data(d);
> +
> + priv->irq_enable |= BIT(d->hwirq);
> +}
> +
> +static void mt7530_irq_bus_lock(struct irq_data *d)
> +{
> + struct mt7530_priv *priv = irq_data_get_irq_chip_data(d);
> +
> + mutex_lock(&priv->reg_mutex);
Are you always guaranteed to be in a thread context? I guess that
is the case, given that you request a threaded interrupt, but
it would be worth documenting.
> +}
> +
> +static void mt7530_irq_bus_sync_unlock(struct irq_data *d)
> +{
> + struct mt7530_priv *priv = irq_data_get_irq_chip_data(d);
> +
> + mt7530_write(priv, MT7530_SYS_INT_EN, priv->irq_enable);
> + mutex_unlock(&priv->reg_mutex);
> +}
> +
> +static struct irq_chip mt7530_irq_chip = {
> + .name = MT7530_NAME,
> + .irq_mask = mt7530_irq_mask,
> + .irq_unmask = mt7530_irq_unmask,
> + .irq_bus_lock = mt7530_irq_bus_lock,
> + .irq_bus_sync_unlock = mt7530_irq_bus_sync_unlock,
> +};
> +
> +static int
> +mt7530_irq_map(struct irq_domain *domain, unsigned int irq,
> + irq_hw_number_t hwirq)
> +{
> + irq_set_chip_data(irq, domain->host_data);
> + irq_set_chip_and_handler(irq, &mt7530_irq_chip, handle_simple_irq);
> + irq_set_noprobe(irq);
> +
> + return 0;
> +}
> +
> +static const struct irq_domain_ops mt7530_irq_domain_ops = {
> + .map = mt7530_irq_map,
> + .xlate = irq_domain_xlate_onecell,
> +};
> +
> +static void
> +mt7530_irq_init(struct mt7530_priv *priv)
> +{
> + struct mii_bus *bus = priv->ds->slave_mii_bus;
> + struct device *dev = priv->dev;
> + struct device_node *np = dev->of_node;
> + int parent_irq;
> + int phy, ret;
> +
> + parent_irq = of_irq_get(np, 0);
> + if (parent_irq <= 0) {
> + dev_err(dev, "failed to get parent IRQ: %d\n", parent_irq);
> + return;
It seems odd not to propagate the error, since I assume the device will
not be functional.
> + }
> +
> + mt7530_set(priv, MT7530_TOP_SIG_CTRL, TOP_SIG_CTRL_NORMAL);
> + ret = devm_request_threaded_irq(dev, parent_irq, NULL, mt7530_irq,
> + IRQF_ONESHOT, MT7530_NAME, priv);
> + if (ret) {
> + dev_err(dev, "failed to request IRQ: %d\n", ret);
> + return;
> + }
> +
> + priv->irq_domain = irq_domain_add_linear(np, MT7530_NUM_PHYS,
> + &mt7530_irq_domain_ops, priv);
The creation order is... interesting. You have a handler ready to fire,
nothing seems to initialise the HW state, and the priv data structure
is not fully populated. If any interrupt is pending at this stage,
you have a panic in your hands.
> + if (!priv->irq_domain) {
> + dev_err(dev, "failed to create IRQ domain\n");
> + return;
> + }
> +
> + /* IRQ for internal PHYs */
> + for (phy = 0; phy < MT7530_NUM_PHYS; phy++) {
> + unsigned int irq = irq_create_mapping(priv->irq_domain, phy);
Why are you eagerly creating all the interrupt mappings? They should be
created on demand as the endpoint drivers come up.
> +
> + irq_set_parent(irq, parent_irq);
> + bus->irq[phy] = irq;
> + }
> +}
> +
> static int
> mt7530_setup(struct dsa_switch *ds)
> {
> @@ -2578,8 +2698,13 @@ static int
> mt753x_setup(struct dsa_switch *ds)
> {
> struct mt7530_priv *priv = ds->priv;
> + int ret = priv->info->sw_setup(ds);
>
> - return priv->info->sw_setup(ds);
> + /* Setup interrupt */
> + if (!ret)
> + mt7530_irq_init(priv);
> +
> + return ret;
> }
>
> static int
> @@ -2780,6 +2905,9 @@ mt7530_remove(struct mdio_device *mdiodev)
> dev_err(priv->dev, "Failed to disable io pwr: %d\n",
> ret);
>
> + if (priv->irq_domain)
> + irq_domain_remove(priv->irq_domain);
See the comment in front of irq_domain_remove() about the need
to discard the mappings prior to removing a domain.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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