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Posted: **Wed Aug 24, 2022 3:40 pm**

Hi All,

Here is the RC2 of kernel 6.0 for testing.

New:

Linux 6.0-rc2 Released -- phoronix.com
Linux 6.0-rc1 Released With Exciting Performance Optimizations, New Hardware Support -- phoronix.com
Many VirtIO Changes Land For Linux 6.0 -- phoronix.com
XFS Scalability Improvement, Other File-System Enhancements Land In Linux 6.0 -- phoronix.com
Linux 6.0 Brings NFSD Improvements For Courteous Server, Greater Cache Scalability -- phoronix.com
6.0-rc2 announcement
6.0-rc1 announcement
X5000: dpaa_v8 patch because of the DPAA issue on Ubuntu 16.04
PowerPC fixes 6.0-3
PowerPC fixes 6.0-2
PowerPC updates 6.0-1
CONFIG_SND_CTL_FAST_LOOKUP=y
Linux Git log
Phoronix articles, reviews and news stories covering Linux 6.0

Download: linux-image-6.0-rc2-X1000_X5000.tar.gz

Please test the kernels.

Thanks,
Christian

Posted: **Thu Aug 25, 2022 2:40 pm**

Arminder Singh will add IRQ support for Apple Silicon to some pasemi source files in the Linux kernel.

Arminder Singh wrote: This is the first time I'm interacting with the Linux mailing lists, so
please don't eviscerate me *too much* if I get the formatting wrong.
Of course I'm always willing to take criticism and improve my formatting
in the future.

This patch adds support for IRQs to the PASemi I2C controller driver.
This will allow for faster performing I2C transactions on Apple Silicon
hardware, as previously, the driver was forced to poll the SMSTA register
for a set amount of time.

With this patchset the driver on Apple silicon hardware will instead wait
for an interrupt which will signal the completion of the I2C transaction.
The timeout value for this completion will be the same as the current
amount of time the I2C driver polls for.

This will result in some performance improvement since the driver will be
waiting for less time than it does right now on Apple Silicon hardware.

The patch right now will only enable IRQs for Apple Silicon I2C chips,
and only if it's able to successfully request the IRQ from the kernel.

=== Testing ===

This patch has been tested on both the mainline Linux kernel tree and
the Asahi branch (https://github.com/AsahiLinux/linux.git) on both an
M1 and M2 MacBook Air, and it compiles successfully as both a module and
built-in to the kernel itself. The patch in both trees successfully boots
to userspace without any hitch.

I do not have PASemi hardware on hand unfortunately, so I'm unable to test
the impact of this patch on old PASemi hardware. This is also why I've
elected to do the IRQ request and enablement on the Apple platform driver
and not in the common file, as I'm not sure if PASemi hardware supports
IRQs.

I also fixed a quick checkpatch warning on line 303. "i ++" is now "i++".

Any and all critiques of the patch would be well appreciated.

i2c-pasemi_apple_silicon.patch:

Code: Select all

diff --git a/drivers/i2c/busses/i2c-pasemi-core.c b/drivers/i2c/busses/i2c-pasemi-core.c
index 9028ffb58cc0..375aa9528233 100644
--- a/drivers/i2c/busses/i2c-pasemi-core.c
+++ b/drivers/i2c/busses/i2c-pasemi-core.c
@@ -21,6 +21,7 @@
 #define REG_MTXFIFO	0x00
 #define REG_MRXFIFO	0x04
 #define REG_SMSTA	0x14
+#define REG_IMASK   0x18
 #define REG_CTL		0x1c
 #define REG_REV		0x28
 
@@ -80,14 +81,21 @@ static int pasemi_smb_waitready(struct pasemi_smbus *smbus)
 {
 	int timeout = 10;
 	unsigned int status;
+	unsigned int bitmask = SMSTA_XEN | SMSTA_MTN;
 
-	status = reg_read(smbus, REG_SMSTA);
-
-	while (!(status & SMSTA_XEN) && timeout--) {
-		msleep(1);
+	if (smbus->use_irq) {
+		reinit_completion(&smbus->irq_completion);
+		reg_write(smbus, REG_IMASK, bitmask);
+		wait_for_completion_timeout(&smbus->irq_completion, msecs_to_jiffies(10));
 		status = reg_read(smbus, REG_SMSTA);
+	} else {
+		while (!(status & SMSTA_XEN) && timeout--) {
+			msleep(1);
+			status = reg_read(smbus, REG_SMSTA);
+		}
 	}
 
+
 	/* Got NACK? */
 	if (status & SMSTA_MTN)
 		return -ENXIO;
@@ -300,7 +308,7 @@ static int pasemi_smb_xfer(struct i2c_adapter *adapter,
 	case I2C_SMBUS_BLOCK_DATA:
 	case I2C_SMBUS_BLOCK_PROC_CALL:
 		data->block[0] = len;
-		for (i = 1; i <= len; i ++) {
+		for (i = 1; i <= len; i++) {
 			rd = RXFIFO_RD(smbus);
 			if (rd & MRXFIFO_EMPTY) {
 				err = -ENODATA;
@@ -348,6 +356,8 @@ int pasemi_i2c_common_probe(struct pasemi_smbus *smbus)
 	if (smbus->hw_rev != PASEMI_HW_REV_PCI)
 		smbus->hw_rev = reg_read(smbus, REG_REV);
 
+	reg_write(smbus, REG_IMASK, 0);
+
 	pasemi_reset(smbus);
 
 	error = devm_i2c_add_adapter(smbus->dev, &smbus->adapter);
@@ -356,3 +366,12 @@ int pasemi_i2c_common_probe(struct pasemi_smbus *smbus)
 
 	return 0;
 }
+
+irqreturn_t pasemi_irq_handler(int irq, void *dev_id)
+{
+	struct pasemi_smbus *smbus = (struct pasemi_smbus *)dev_id;
+
+	reg_write(smbus, REG_IMASK, 0);
+	complete(&smbus->irq_completion);
+	return IRQ_HANDLED;
+}
diff --git a/drivers/i2c/busses/i2c-pasemi-core.h b/drivers/i2c/busses/i2c-pasemi-core.h
index 4655124a37f3..045e4a9a3d13 100644
--- a/drivers/i2c/busses/i2c-pasemi-core.h
+++ b/drivers/i2c/busses/i2c-pasemi-core.h
@@ -7,6 +7,7 @@
 #include <linux/i2c-smbus.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
+#include <linux/completion.h>
 
 #define PASEMI_HW_REV_PCI -1
 
@@ -16,6 +17,10 @@ struct pasemi_smbus {
 	void __iomem		*ioaddr;
 	unsigned int		 clk_div;
 	int			 hw_rev;
+	int          use_irq;
+	struct completion irq_completion;
 };
 
 int pasemi_i2c_common_probe(struct pasemi_smbus *smbus);
+
+irqreturn_t pasemi_irq_handler(int irq, void *dev_id);
diff --git a/drivers/i2c/busses/i2c-pasemi-platform.c b/drivers/i2c/busses/i2c-pasemi-platform.c
index 88a54aaf7e3c..ee1c84e7734b 100644
--- a/drivers/i2c/busses/i2c-pasemi-platform.c
+++ b/drivers/i2c/busses/i2c-pasemi-platform.c
@@ -49,6 +49,7 @@ static int pasemi_platform_i2c_probe(struct platform_device *pdev)
 	struct pasemi_smbus *smbus;
 	u32 frequency;
 	int error;
+	int irq_num;
 
 	data = devm_kzalloc(dev, sizeof(struct pasemi_platform_i2c_data),
 			    GFP_KERNEL);
@@ -82,6 +83,13 @@ static int pasemi_platform_i2c_probe(struct platform_device *pdev)
 	if (error)
 		goto out_clk_disable;
 
+	smbus->use_irq = 0;
+	init_completion(&smbus->irq_completion);
+	irq_num = platform_get_irq(pdev, 0);
+	error = request_irq(irq_num, pasemi_irq_handler, 0, "pasemi_apple_i2c", (void *)smbus);
+
+	if (!error)
+		smbus->use_irq = 1;
 	platform_set_drvdata(pdev, data);
 
 	return 0;

Michael Ellerman wrote: I've added Darren and Christian to Cc, they have helped with PASemi
development and testing in the past, and may be able to help test this
series on PASemi hardware.

cheers

I will test Arminder's patch.

Posted: **Thu Aug 25, 2022 4:54 pm**

I compiled a new test kernel with Arminder's patch today and it works without any problems.

Download: linux-image-6.0-rc2-2-X1000.tar.gz

Link to the thread: [PATCH] i2c: pasemi: Add IRQ support for Apple Silicon -- linuxppc-dev

Posted: **Thu Aug 25, 2022 9:00 pm**

my x1000 does not boot on linux-6-0 I get a kernel panic.
I have tried with fat16 and fat32 on my USB disk. Same result
Have a nice day

Posted: **Fri Aug 26, 2022 1:22 pm**

musa wrote: Thu Aug 25, 2022 9:00 pm my x1000 does not boot on linux-6-0 I get a kernel panic.
I have tried with fat16 and fat32 on my USB disk. Same result
Have a nice day

My X1000 boots and works with the kernels 6.0-rc2 and rc2-2. Have you seen any error messages?

Posted: **Fri Aug 26, 2022 5:49 pm**

@All
The following command is great for figuring out very fast kernel issues.

Code: Select all

dmesg -x -l crit,warn,err

Posted: **Fri Aug 26, 2022 11:10 pm**

First try was with Mint and fail.
The next attempt is with Debian Bookworm and this time its successful.
I try Mint later again.
Have a nice day

Posted: **Sat Aug 27, 2022 12:44 pm**

musa wrote: Fri Aug 26, 2022 11:10 pm First try was with Mint and fail.
The next attempt is with Debian Bookworm and this time its successful.
I try Mint later again.
Have a nice day

Good to know. Thanks a lot for testing!

Posted: **Sat Aug 27, 2022 9:52 pm**

Mint now also runs with vmlinux-6.0 rc2.2 on my X1000.
I find a cluster error on my usbdisk.
After fixing this error mint booted fine.
Have a nice day

Posted: **Sat Aug 27, 2022 11:59 pm**

musa wrote: Sat Aug 27, 2022 9:52 pm Mint now also runs with vmlinux-6.0 rc2.2 on my X1000.
I find a cluster error on my usbdisk.
After fixing this error mint booted fine.
Have a nice day

Great!

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