linux-kernel - [PATCH v6 1/5] i2c: designware: Use polling by default when there is no irq resource

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250701122252.2590230-2-heikki.krogerus@linux.intel.com>
Date: Tue,  1 Jul 2025 15:22:48 +0300
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: Lucas De Marchi <lucas.demarchi@...el.com>,
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>
Cc: Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Jan Dabros <jsd@...ihalf.com>,
	Andi Shyti <andi.shyti@...nel.org>,
	Raag Jadav <raag.jadav@...el.com>,
	"Tauro, Riana" <riana.tauro@...el.com>,
	"Adatrao, Srinivasa" <srinivasa.adatrao@...el.com>,
	"Michael J. Ruhl" <michael.j.ruhl@...el.com>,
	intel-xe@...ts.freedesktop.org,
	linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v6 1/5] i2c: designware: Use polling by default when there is no irq resource

The irq resource itself can be used as a generic way to
determine when polling is needed.

This not only removes the need for special additional device
properties that would soon be needed when the platform may
or may not have the irq, but it also removes the need to
check the platform in the first place in order to determine
is polling needed or not.

Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
---
Hi guys,

I found the thread with Jarkko's comments from my archives. He wanted
the local flags variable to be added because he wants the order of the
calls to remain as it is now - the device is allocated only after the
irq is checked.

thanks,
---
 drivers/i2c/busses/i2c-designware-platdrv.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 879719e91df2..3104f52e32be 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -205,25 +205,28 @@ static void i2c_dw_remove_lock_support(struct dw_i2c_dev *dev)
 
 static int dw_i2c_plat_probe(struct platform_device *pdev)
 {
+	u32 flags = (uintptr_t)device_get_match_data(&pdev->dev);
 	struct device *device = &pdev->dev;
 	struct i2c_adapter *adap;
 	struct dw_i2c_dev *dev;
 	int irq, ret;
 
-	irq = platform_get_irq(pdev, 0);
-	if (irq < 0)
+	irq = platform_get_irq_optional(pdev, 0);
+	if (irq == -ENXIO)
+		flags |= ACCESS_POLLING;
+	else if (irq < 0)
 		return irq;
 
 	dev = devm_kzalloc(device, sizeof(*dev), GFP_KERNEL);
 	if (!dev)
 		return -ENOMEM;
 
-	dev->flags = (uintptr_t)device_get_match_data(device);
 	if (device_property_present(device, "wx,i2c-snps-model"))
-		dev->flags = MODEL_WANGXUN_SP | ACCESS_POLLING;
+		flags = MODEL_WANGXUN_SP | ACCESS_POLLING;
 
 	dev->dev = device;
 	dev->irq = irq;
+	dev->flags = flags;
 	platform_set_drvdata(pdev, dev);
 
 	ret = dw_i2c_plat_request_regs(dev);
-- 
2.47.2