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Message-ID: <20170721164900.7070-1-grygorii.strashko@ti.com>
Date: Fri, 21 Jul 2017 11:49:00 -0500
From: Grygorii Strashko <grygorii.strashko@...com>
To: Linus Walleij <linus.walleij@...aro.org>,
<linux-gpio@...r.kernel.org>
CC: <linux-kernel@...r.kernel.org>,
Jerome Brunet <jbrunet@...libre.com>,
Grygorii Strashko <grygorii.strashko@...com>
Subject: [RFT PATCH v2] gpiolib: allow gpio irqchip to map irqs dynamically
Now IRQ mappings are always created for all (allowed) GPIOs in gpiochip in
gpiochip_irqchip_add_key() which goes against the idea of SPARSE_IRQ and,
as result, leads to:
- increasing of memory consumption for IRQ descriptors most of which will
never ever be used (espessially on platform with a high number of GPIOs).
(sizeof(struct irq_desc) == 256 on my tested platforms)
- imposibility to use GPIO irqchip APIs by gpio drivers when HW implements
GPIO IRQ functionality as IRQ crossbar/router which has only limited
number of IRQ outputs (example from [1], all GPIOs can be mapped on only 8
IRQs).
Hence, remove static IRQ mapping code from gpiochip_irqchip_add_key() and
instead replace irq_find_mapping() with irq_create_mapping() in
gpiochip_to_irq(). Also add additional gpiochip_irqchip_irq_valid() calls
in gpiochip_to_irq() and gpiochip_irq_map().
After this change gpio2irq mapping will happen the following way when GPIO
irqchip APIs are used by gpio driver:
- IRQ mappings will be created statically if driver passes first_irq>0
vlaue in gpiochip_irqchip_add_key().
- IRQ mappings will be created dynamically from gpio_to_irq() or
of_irq_get().
Tested on am335x-evm and dra72-evm-revc.
- dra72-evm-revc: number of created irq mappings decreased from 402 -> 135
Mem savings 267*256 = 68352 (66kB)
- am335x-evm: number of created irq mappings decreased from 188 -> 63
Mem savings 125*256 = 32000 (31kB)
[1] https://lkml.org/lkml/2017/6/15/428
Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
---
Changes in v2:
- restored struct gpio_chip->irq_base to fix buld of gpio-mockup.c
Link on v1:
- https://patchwork.kernel.org/patch/9831565/
drivers/gpio/gpiolib.c | 29 ++++++-----------------------
1 file changed, 6 insertions(+), 23 deletions(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 9568708..ee6ba07 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1605,6 +1605,9 @@ static int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
{
struct gpio_chip *chip = d->host_data;
+ if (!gpiochip_irqchip_irq_valid(chip, hwirq))
+ return -ENXIO;
+
irq_set_chip_data(irq, chip);
/*
* This lock class tells lockdep that GPIO irqs are in a different
@@ -1671,7 +1674,9 @@ static void gpiochip_irq_relres(struct irq_data *d)
static int gpiochip_to_irq(struct gpio_chip *chip, unsigned offset)
{
- return irq_find_mapping(chip->irqdomain, offset);
+ if (!gpiochip_irqchip_irq_valid(chip, offset))
+ return -ENXIO;
+ return irq_create_mapping(chip->irqdomain, offset);
}
/**
@@ -1747,9 +1752,6 @@ int gpiochip_irqchip_add_key(struct gpio_chip *gpiochip,
struct lock_class_key *lock_key)
{
struct device_node *of_node;
- bool irq_base_set = false;
- unsigned int offset;
- unsigned irq_base = 0;
if (!gpiochip || !irqchip)
return -EINVAL;
@@ -1806,25 +1808,6 @@ int gpiochip_irqchip_add_key(struct gpio_chip *gpiochip,
irqchip->irq_release_resources = gpiochip_irq_relres;
}
- /*
- * Prepare the mapping since the irqchip shall be orthogonal to
- * any gpiochip calls. If the first_irq was zero, this is
- * necessary to allocate descriptors for all IRQs.
- */
- for (offset = 0; offset < gpiochip->ngpio; offset++) {
- if (!gpiochip_irqchip_irq_valid(gpiochip, offset))
- continue;
- irq_base = irq_create_mapping(gpiochip->irqdomain, offset);
- if (!irq_base_set) {
- /*
- * Store the base into the gpiochip to be used when
- * unmapping the irqs.
- */
- gpiochip->irq_base = irq_base;
- irq_base_set = true;
- }
- }
-
acpi_gpiochip_request_interrupts(gpiochip);
return 0;
--
2.10.1
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