Messages in this thread | | | Subject | Re: [PATCH v2 1/2] acpi, spcr: Make SPCR avialable to other architectures | From | Timur Tabi <> | Date | Wed, 13 Dec 2017 15:11:33 -0600 |
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On 12/13/2017 06:45 AM, Lorenzo Pieralisi wrote: >> +/* >> + * Erratum 44 for QDF2432v1 and QDF2400v1 SoCs describes the BUSY bit as >> + * occasionally getting stuck as 1. To avoid the potential for a hang, check >> + * TXFE == 0 instead of BUSY == 1. This may not be suitable for all UART >> + * implementations, so only do so if an affected platform is detected in >> + * acpi_parse_spcr(). >> + */ >> +bool qdf2400_e44_present; >> +EXPORT_SYMBOL(qdf2400_e44_present); > > My eyes, this is horrible but it is not introduced by this patch. It > would have been much better if: > > drivers/tty/serial/amba-pl011.c > > parsed the SPCR table (again) to detect it instead of relying on this > horrible exported flag.
I didn't want to put any ACPI code in amba-pl011.c, so putting it in spcr.c made the most sense. I agree the global variable is ugly. If you have a better idea, I'm all ears.
If it's any consolation, this erratum affects only 1.x silicon, which is technically pre-production (although a lot of people have them). This work-around will eventually be reverted.
>> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig >> index 46505396869e..9ae98eeada76 100644 >> --- a/drivers/acpi/Kconfig >> +++ b/drivers/acpi/Kconfig >> @@ -79,7 +79,12 @@ config ACPI_DEBUGGER_USER >> endif >> >> config ACPI_SPCR_TABLE >> - bool >> + bool "ACPI Serial Port Console Redirection Support" >> + default y if ARM64 > > You need to remove the selection in arch/arm64 then. Also, moving away > from a non-visible config may have consequences on ARM64, Graeme and > Mark are more familiar with the SPCR dependencies so please chime in.
I did raise this as a concern in the previous version of the patch. I also think it should not be a selectable option.
Keeping the "select" does force SPCR to be enabled on ARM64 ACPI platforms, but if it's an option for x86, it should be an option for ARM.
-- Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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