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Commit e284175a authored by Jiang Liu's avatar Jiang Liu Committed by Rafael J. Wysocki
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ACPI / nouveau: fix probing regression related to _DSM 



Fix regression caused by commit b072e53b, 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.

Fixes: b072e53b (ACPI / nouveau: replace open-coded _DSM code with helper functions)
Reported-and-tested-by: default avatarMaarten Lankhorst <maarten.lankhorst@canonical.com>
[rjw: Subject]
Signed-off-by: default avatarJiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 6d0abeca

drivers/gpu/drm/nouveau/nouveau_acpi.c

+24 −2
Original line number Diff line number Diff line
@@ -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) {