Hi Christophe
This part of the code is not a hotspot path. In fact, it may only be
executed once at startup,
so some optimizations that we consider extreme can be omitted
Tianyang
在 2024/3/16 下午10:03, Christophe JAILLET 写道:
Le 16/03/2024 à 09:21, Tianyang Zhang a écrit :
From: Baoqi Zhang <zhangbaoqi@xxxxxxxxxxx>
This patch remove the fixed mapping between the 7A interrupt source
and the HT interrupt vector, and replaced it with a dynamically
allocated approach.
We introduce a mapping table in struct pch_pic, where each interrupt
source will allocate an index as a 'hwirq' from the table in the order
of application and set table value as interrupt source number. This
hwirq
will be configured as its vector in the HT interrupt controller. For an
interrupt source, the validity period of the obtained hwirq will last
until
the system reset
This will be more conducive to fully utilizing existing vectors to
support more devices
Signed-off-by: Baoqi Zhang <zhangbaoqi@xxxxxxxxxxx>
Signed-off-by: Biao Dong <dongbiao@xxxxxxxxxxx>
Signed-off-by: Tianyang Zhang <zhangtianyang@xxxxxxxxxxx>
---
drivers/irqchip/irq-loongson-pch-pic.c | 77 ++++++++++++++++++++------
1 file changed, 59 insertions(+), 18 deletions(-)
...
@@ -171,6 +183,27 @@ static int pch_pic_domain_translate(struct
irq_domain *d,
return -EINVAL;
*hwirq = fwspec->param[0] - priv->gsi_base;
+
+ raw_spin_lock_irqsave(&priv->pic_lock, flags);
+ /* Check pic-table to confirm if the hwirq has been assigned */
+ for (i = 0; i < priv->inuse; i++) {
+ if (priv->table[i] == *hwirq) {
+ *hwirq = i;
+ break;
+ }
+ }
+ if (i == priv->inuse) {
+ /* Assign a new hwirq in pic-table */
+ if (priv->inuse >= PIC_COUNT) {
+ pr_err("pch-pic domain has no free vectors\n");
+ raw_spin_unlock_irqrestore(&priv->pic_lock, flags);
+ return -EINVAL;
+ }
+ priv->table[priv->inuse] = *hwirq;
+ *hwirq = priv->inuse++;
+ }
+ raw_spin_unlock_irqrestore(&priv->pic_lock, flags);
Hi,
not sure if it helps or if this is a hot path, but, IIUC, taking the
lock could be avoided with some code reordering and 'inuse' being an
atomic_t.
IIUC, the lock is only needed to protect 'inuse' and 'table' is never
modified afterwards.
Somehing like:
> + int cur_inuse;
...
> + cur_inuse = atomic_read(&priv->inuse);
> + /* Check pic-table to confirm if the hwirq has been
assigned */
> + for (i = 0; i < cur_inuse; i++) {
> + if (priv->table[i] == *hwirq) {
> + *hwirq = i;
> + break;
> + }
> + }
> + if (i == cur_inuse) {
> + /* Assign a new hwirq in pic-table */
> + if (cur_inuse >= PIC_COUNT) {
> + pr_err("pch-pic domain has no free vectors\n");
> + return -EINVAL;
> + }
> + priv->table[cur_inuse] = *hwirq;
> + *hwirq = atomic_inc_return(&priv->inuse);
> + }
+
if (fwspec->param_count > 1)
*type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
else
@@ -194,6 +227,9 @@ static int pch_pic_alloc(struct irq_domain
*domain, unsigned int virq,
if (err)
return err;
+ /* Write vector ID */
+ writeb(priv->ht_vec_base + hwirq, priv->base +
PCH_INT_HTVEC(hwirq_to_bit(priv, hwirq)));
+
parent_fwspec.fwnode = domain->parent->fwnode;
parent_fwspec.param_count = 1;
parent_fwspec.param[0] = hwirq + priv->ht_vec_base;
...
