[PATCH v2 0/2] apple-gmux: Fixes related to 'Support for new hardware'

[PATCH v2 0/2] apple-gmux: Fixes related to 'Support for new hardware'

[Bernhard Froemel]

Hello,

it follows a refined version where thanks to Seth and his extensive x86
assembly knowledge my initial assumption about how Apple does byte
writes could be falsified. It appears that byte writes only failed
because the index protocol was not correctly followed in the read functions.

Cheers,
 Bernhard

[PATCH v2 1/2] apple-gmux: Fix index read functions

[Bernhard Froemel]

From: Bernhard Froemel <froemel@vmars.tuwien.ac.at>

Study of Apple's binary driver revealed that the GMUX_READ_PORT should
be written between calls to gmux_index_wait_ready and
gmux_index_wait_complete (i.e., the new index protocol must be
followed). If this is not done correctly, the indexed
gmux device only partially accepts writes which lead to problems
concerning GPU switching. Special thanks to Seth Forshee who helped
greatly with identifying unnecessary changes.

Signed-off-by: Bernhard Froemel <froemel@vmars.tuwien.ac.at>
---
 drivers/platform/x86/apple-gmux.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index dfb1a92..c38538e 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -142,8 +142,9 @@ static u8 gmux_index_read8(struct apple_gmux_data *gmux_data, int port)
 	u8 val;
 
 	mutex_lock(&gmux_data->index_lock);
-	outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ);
 	gmux_index_wait_ready(gmux_data);
+	outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ);
+	gmux_index_wait_complete(gmux_data);
 	val = inb(gmux_data->iostart + GMUX_PORT_VALUE);
 	mutex_unlock(&gmux_data->index_lock);
 
@@ -166,8 +167,9 @@ static u32 gmux_index_read32(struct apple_gmux_data *gmux_data, int port)
 	u32 val;
 
 	mutex_lock(&gmux_data->index_lock);
-	outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ);
 	gmux_index_wait_ready(gmux_data);
+	outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ);
+	gmux_index_wait_complete(gmux_data);
 	val = inl(gmux_data->iostart + GMUX_PORT_VALUE);
 	mutex_unlock(&gmux_data->index_lock);
 
-- 
1.7.9.5

[PATCH v2 2/2] apple-gmux: Obtain version info from indexed gmux

[Bernhard Froemel]

From: Bernhard Froemel <froemel@vmars.tuwien.ac.at>

This patch extracts and displays version information from the indexed
gmux device as it is also done for the classic gmux device.

Signed-off-by: Bernhard Froemel <froemel@vmars.tuwien.ac.at>
---
 drivers/platform/x86/apple-gmux.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index c38538e..0e43477 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -463,18 +463,22 @@ static int __devinit gmux_probe(struct pnp_dev *pnp,
 	ver_release = gmux_read8(gmux_data, GMUX_PORT_VERSION_RELEASE);
 	if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
 		if (gmux_is_indexed(gmux_data)) {
+			u32 version;
 			mutex_init(&gmux_data->index_lock);
 			gmux_data->indexed = true;
+			version = gmux_read32(gmux_data,
+				GMUX_PORT_VERSION_MAJOR);
+			ver_major = (version >> 24) & 0xff;
+			ver_minor = (version >> 16) & 0xff;
+			ver_release = (version >> 8) & 0xff;
 		} else {
 			pr_info("gmux device not present\n");
 			ret = -ENODEV;
 			goto err_release;
 		}
-		pr_info("Found indexed gmux\n");
-	} else {
-		pr_info("Found gmux version %d.%d.%d\n", ver_major, ver_minor,
-			ver_release);
 	}
+	pr_info("Found gmux version %d.%d.%d [%s]\n", ver_major, ver_minor,
+		ver_release, (gmux_data->indexed ? "indexed" : "classic"));
 
 	memset(&props, 0, sizeof(props));
 	props.type = BACKLIGHT_PLATFORM;
-- 
1.7.9.5

Re: [PATCH v2 1/2] apple-gmux: Fix index read functions

[Henrik Rydberg]

On Sat, Aug 25, 2012 at 10:30:48AM +0200, Bernhard Froemel wrote:
> From: Bernhard Froemel <froemel@vmars.tuwien.ac.at>
> 
> Study of Apple's binary driver revealed that the GMUX_READ_PORT should
> be written between calls to gmux_index_wait_ready and
> gmux_index_wait_complete (i.e., the new index protocol must be
> followed). If this is not done correctly, the indexed
> gmux device only partially accepts writes which lead to problems
> concerning GPU switching. Special thanks to Seth Forshee who helped
> greatly with identifying unnecessary changes.
> 
> Signed-off-by: Bernhard Froemel <froemel@vmars.tuwien.ac.at>
> ---

Hi Bernhard,

thanks for your patch, this works splendidly; I can resume and select
different screen resolutions using xrandr.

    Tested-by: Henrik Rydberg <rydberg@euromail.se>

Henrik

Re: [PATCH v2 1/2] apple-gmux: Fix index read functions

[Seth Forshee]

On Sat, Aug 25, 2012 at 10:30:48AM +0200, Bernhard Froemel wrote:
> From: Bernhard Froemel <froemel@vmars.tuwien.ac.at>
> 
> Study of Apple's binary driver revealed that the GMUX_READ_PORT should
> be written between calls to gmux_index_wait_ready and
> gmux_index_wait_complete (i.e., the new index protocol must be
> followed). If this is not done correctly, the indexed
> gmux device only partially accepts writes which lead to problems
> concerning GPU switching. Special thanks to Seth Forshee who helped
> greatly with identifying unnecessary changes.
> 
> Signed-off-by: Bernhard Froemel <froemel@vmars.tuwien.ac.at>

This does better match what Apple's driver does. Thanks Bernhard.

Acked-by: Seth Forshee <seth.forshee@canonical.com>

Re: [PATCH v2 2/2] apple-gmux: Obtain version info from indexed gmux

[Seth Forshee]

On Sat, Aug 25, 2012 at 10:30:49AM +0200, Bernhard Froemel wrote:
> From: Bernhard Froemel <froemel@vmars.tuwien.ac.at>
> 
> This patch extracts and displays version information from the indexed
> gmux device as it is also done for the classic gmux device.
> 
> Signed-off-by: Bernhard Froemel <froemel@vmars.tuwien.ac.at>

Acked-by: Seth Forshee <seth.forshee@canonical.com>