Originally by Seth Forshee <seth.forshee at canonical.com>, 2012-10-04: Some dual graphics machines support muxing the DDC separately from the display, so make use of this functionality when reading the EDID on the inactive GPU. Also serialize drm_get_edid() with a mutex to avoid races on the DDC mux state.
Modified by Dave Airlie <airlied at gmail.com>, 2012-12-22: I can't figure out why I didn't like this, but I rewrote this [...] to lock/unlock the ddc lines [...]. I think I'd prefer something like that otherwise the interface got really ugly. Modified by Lukas Wunner <lukas at wunner.de>, 2015-03-27: Unlock DDC lines if drm_probe_ddc() fails. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88861 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61115 Tested-by: Pierre Moreau <pierre.morrow at free.fr> [MBP 5,3 2009 nvidia 9400M + 9600M GT pre-retina] Tested-by: Paul Hordiienko <pvt.gord at gmail.com> [MBP 6,2 2010 intel ILK + nvidia GT216 pre-retina] Tested-by: William Brown <william at blackhats.net.au> [MBP 8,2 2011 intel SNB + amd turks pre-retina] Tested-by: Lukas Wunner <lukas at wunner.de> [MBP 9,1 2012 intel IVB + nvidia GK107 pre-retina] Tested-by: Bruno Bierbaumer <bruno at bierbaumer.net> [MBP 11,3 2013 intel HSW + nvidia GK107 retina -- work in progress] Cc: Seth Forshee <seth.forshee at canonical.com> Cc: Dave Airlie <airlied at gmail.com> Signed-off-by: Lukas Wunner <lukas at wunner.de> --- drivers/gpu/drm/drm_edid.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index e6e05bb..cdb2fa1 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -32,6 +32,7 @@ #include <linux/hdmi.h> #include <linux/i2c.h> #include <linux/module.h> +#include <linux/vga_switcheroo.h> #include <drm/drmP.h> #include <drm/drm_edid.h> #include <drm/drm_displayid.h> @@ -1377,13 +1378,21 @@ struct edid *drm_get_edid(struct drm_connector *connector, struct i2c_adapter *adapter) { struct edid *edid; + struct pci_dev *pdev = connector->dev->pdev; - if (!drm_probe_ddc(adapter)) + vga_switcheroo_lock_ddc(pdev); + + if (!drm_probe_ddc(adapter)) { + vga_switcheroo_unlock_ddc(pdev); return NULL; + } edid = drm_do_get_edid(connector, drm_do_probe_ddc_edid, adapter); if (edid) drm_get_displayid(connector, edid); + + vga_switcheroo_unlock_ddc(pdev); + return edid; } EXPORT_SYMBOL(drm_get_edid); -- 2.1.0