Thanks, Rafael. Will cc ACPI maillist next time.

On 2014/2/21 4:27, Rafael J. Wysocki wrote:

On 2/20/2014 10:23 AM, Jiang Liu wrote:

...

Fix regression caused by commit b072e53, which breaks loading nouveau driver on optimus laptops.

On some platforms, ACPI _DSM method (nouveau_op_dsm_muid, function 0) has special requirements on the fourth parameter, which is different from ACPI specifications. So revert to the private implementation to check availability of _DSM functions instead of using common acpi_check_dsm() interface.

Reported-and-Tested-by: Maarten Lankhorst maarten.lankhorst@canonical.com Signed-off-by: Jiang Liu jiang.liu@linux.intel.com

I'm taking this, because the commit that introduced the regression went in through my tree.

In the future I'll appreciate CCing ACPI-related patches to linux-acpi, however.

Thanks, Rafael

...

---

drivers/gpu/drm/nouveau/nouveau_acpi.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c b/drivers/gpu/drm/nouveau/nouveau_acpi.c index 4ef83df..83face3 100644 --- a/drivers/gpu/drm/nouveau/nouveau_acpi.c +++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c @@ -106,6 +106,29 @@ static int nouveau_optimus_dsm(acpi_handle handle, int func, int arg, uint32_t * return 0; } +/*

• • On some platforms, _DSM(nouveau_op_dsm_muid, func0) has special
• • requirements on the fourth parameter, so a private implementation
• • instead of using acpi_check_dsm().
• */

+static int nouveau_check_optimus_dsm(acpi_handle handle) +{

• int result;
• /*

• * Function 0 returns a Buffer containing available functions.
  

• * The args parameter is ignored for function 0, so just put 0 in it
  

• */
  

• if (nouveau_optimus_dsm(handle, 0, 0, &result))

•    return 0;
  

• /*

• * ACPI Spec v4 9.14.1: if bit 0 is zero, no function is supported.
  

• * If the n-th bit is enabled, function n is supported
  

• */
  

• return result & 1 && result & (1 << NOUVEAU_DSM_OPTIMUS_CAPS);

+}

• static int nouveau_dsm(acpi_handle handle, int func, int arg) { int ret = 0;

@@ -207,8 +230,7 @@ static int nouveau_dsm_pci_probe(struct pci_dev *pdev) 1 << NOUVEAU_DSM_POWER)) retval |= NOUVEAU_DSM_HAS_MUX;

• if (acpi_check_dsm(dhandle, nouveau_op_dsm_muid, 0x00000100,

•           1 << NOUVEAU_DSM_OPTIMUS_CAPS))
  

• if (nouveau_check_optimus_dsm(dhandle)) retval |= NOUVEAU_DSM_HAS_OPT; if (retval & NOUVEAU_DSM_HAS_OPT) {

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