This has already been addressed by two patches to the ACPICA code. See bugzilla 9487. >-----Original Message----- >From: Bjorn Helgaas [mailto:bjorn.helgaas@xxxxxx] >Sent: Wednesday, May 21, 2008 4:25 PM >To: Len Brown; Moore, Robert >Cc: linux-acpi@xxxxxxxxxxxxxxx >Subject: ACPI CA resource encoding problem > >I've tripped over some devices that work with PNPBIOS but not with >PNPACPI, even though Linux is configuring the devices identically. > >Linux evaluates _CRS to get a template, which it then fills in and >passes to _SRS to configure the device. The ACPI CA decodes the AML >bytestream returned from _CRS into a series of acpi_resource structs. > >When Linux evaluates _SRS, the ACPI CA re-encodes the acpi_resource >structs into an AML bytestream. However, the encoded bytestream >sometimes has a different form than that returned from _CRS. > >For example, acpi_rs_set_irq encodes a small IRQ descriptor. If the >IRQ is edge-sensitive, active high, and exclusive, acpi_rs_set_irq >optimizes the output AML by omitting the optional flags byte. > >I think it would be better for acpi_rs_set_irq to generate an AML >descriptor that exactly matches the format and size of the descriptor >we got from _CRS because _SRS may not be smart enough to handle the >variation. > >On a Toshiba Portege 4000, the parport_pc and smsc-ircc2 drivers both >work with PNPBIOS, and neither works with PNPACPI. I think the reason >is this acpi_rs_set_irq optimization. If I apply the attached patch, >which removes that optimization, both drivers work with PNPACPI. > >I don't claim that this patch is correct, because it *always* generates >3-byte IRQ descriptors, while _SRS may be expecting a 2-byte descriptor. >But I think it is enough to point out a problem. > >Bjorn > > >Index: work10/drivers/acpi/resources/rsirq.c >=================================================================== >--- work10.orig/drivers/acpi/resources/rsirq.c 2008-05-21 >15:14:10.000000000 -0600 >+++ work10/drivers/acpi/resources/rsirq.c 2008-05-21 15:15:11.000000000 - >0600 >@@ -152,26 +152,6 @@ struct acpi_rsconvert_info acpi_rs_set_i > /* Reset length to 3 bytes (descriptor with flags byte) */ > > {ACPI_RSC_LENGTH, 0, 0, sizeof(struct aml_resource_irq)}, >- >- /* >- * Check if the flags byte is necessary. Not needed if the flags are: >- * ACPI_EDGE_SENSITIVE, ACPI_ACTIVE_HIGH, ACPI_EXCLUSIVE >- */ >- {ACPI_RSC_EXIT_NE, ACPI_RSC_COMPARE_VALUE, >- ACPI_RS_OFFSET(data.irq.triggering), >- ACPI_EDGE_SENSITIVE}, >- >- {ACPI_RSC_EXIT_NE, ACPI_RSC_COMPARE_VALUE, >- ACPI_RS_OFFSET(data.irq.polarity), >- ACPI_ACTIVE_HIGH}, >- >- {ACPI_RSC_EXIT_NE, ACPI_RSC_COMPARE_VALUE, >- ACPI_RS_OFFSET(data.irq.sharable), >- ACPI_EXCLUSIVE}, >- >- /* We can optimize to a 2-byte irq_no_flags() descriptor */ >- >- {ACPI_RSC_LENGTH, 0, 0, sizeof(struct aml_resource_irq_noflags)} > }; > > >/********************************************************************** **** >***** -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
