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Re: [PATCH V16 09/12] MIPS: Loongson: Add Loongson-3 Kconfig options

To: Alex Smith <alex.smith@imgtec.com>
Subject: Re: [PATCH V16 09/12] MIPS: Loongson: Add Loongson-3 Kconfig options
From: Aurelien Jarno <aurelien@aurel32.net>
Date: Sat, 11 Jan 2014 16:24:07 +0100
Cc: Huacai Chen <chenhc@lemote.com>, Ralf Baechle <ralf@linux-mips.org>, John Crispin <john@phrozen.org>, "Steven J. Hill" <Steven.Hill@imgtec.com>, linux-mips@linux-mips.org, Fuxin Zhang <zhangfx@lemote.com>, Zhangjin Wu <wuzhangjin@gmail.com>, Hongliang Tao <taohl@lemote.com>, Hua Yan <yanh@lemote.com>
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On Thu, Jan 09, 2014 at 01:07:30PM +0000, Alex Smith wrote:
> On 08/01/14 02:44, Huacai Chen wrote:
> >Added Kconfig options include: Loongson-3 CPU and machine definition,
> >CPU cache features, UEFI-like firmware interface (LEFI), HT-linked PCI,
> >and big memory support.
> >
> >Signed-off-by: Huacai Chen <chenhc@lemote.com>
> >Signed-off-by: Hongliang Tao <taohl@lemote.com>
> >Signed-off-by: Hua Yan <yanh@lemote.com>
> >---
> >  arch/mips/Kconfig           |   29 +++++++++++++++++++++++++++-
> >  arch/mips/loongson/Kconfig  |   44 
> > +++++++++++++++++++++++++++++++++++++++++++
> >  arch/mips/loongson/Platform |    1 +
> >  3 files changed, 73 insertions(+), 1 deletions(-)
> >
> >diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> >index 17cc7ff..513e941 100644
> >--- a/arch/mips/Kconfig
> >+++ b/arch/mips/Kconfig
> >@@ -1487,6 +1487,18 @@ config CPU_LOONGSON2
> >     select CPU_SUPPORTS_HIGHMEM
> >     select CPU_SUPPORTS_HUGEPAGES
> >
> >+config CPU_LOONGSON3
> >+    bool "Loongson 3 CPU"
> >+    depends on SYS_HAS_CPU_LOONGSON3
> >+    select CPU_SUPPORTS_64BIT_KERNEL
> >+    select CPU_SUPPORTS_HIGHMEM
> >+    select CPU_SUPPORTS_HUGEPAGES
> >+    select WEAK_ORDERING
> >+    select WEAK_REORDERING_BEYOND_LLSC
> >+    help
> >+            The Loongson 3 processor implements the MIPS III instruction set
> >+            with many extensions.
> >+
> 
> This should be moved into the "CPU type" choice block. Currently
> this appears as an option outside of that choice, and so it is
> possible to build a kernel without any CPU type selected.
> 
> Also, as Aurelien said on the previous version, shouldn't the
> comment be changed to MIPS64R2 rather than MIPS III even if you
> aren't selecting the MIPS64 CPU types for the time being? Note, if
> you replied to that comment I may not have seen it - I think the
> list is filtering your replies because they're HTML emails.
> 
> >  config CPU_LOONGSON1
> >     bool
> >     select CPU_MIPS32
> >@@ -1513,6 +1526,10 @@ config SYS_HAS_CPU_LOONGSON2F
> >     select CPU_SUPPORTS_ADDRWINCFG if 64BIT
> >     select CPU_SUPPORTS_UNCACHED_ACCELERATED
> >
> >+config SYS_HAS_CPU_LOONGSON3
> >+    bool
> >+    select CPU_SUPPORTS_CPUFREQ
> >+
> >  config SYS_HAS_CPU_LOONGSON1B
> >     bool
> >
> >@@ -1703,7 +1720,7 @@ choice
> >
> >  config PAGE_SIZE_4KB
> >     bool "4kB"
> >-    depends on !CPU_LOONGSON2
> >+    depends on !CPU_LOONGSON2 && !CPU_LOONGSON3
> >     help
> >      This option select the standard 4kB Linux page size.  On some
> >      R3000-family processors this is the only available page size.  Using
> >@@ -2373,6 +2390,16 @@ config PCI
> >       your box. Other bus systems are ISA, EISA, or VESA. If you have PCI,
> >       say Y, otherwise N.
> >
> >+config HT_PCI
> >+    bool "Support for HT-linked PCI"
> >+    depends on CPU_LOONGSON3
> >+    select PCI_DOMAINS
> >+    help
> >+      Loongson family machines use Hyper-Transport bus for inter-core
> >+      connection and device connection. The PCI bus is a subordinate
> >+      linked at HT. Choose Y unless you are using Loongson 2E/2F based
> >+      machines.
> >+
> 
> Should this default to y, given that it is selected in the
> defconfig? Also, the comment referring to 2E/2F is redundant given
> that it depends on CPU_LOONGSON3 and cannot be selected on those
> machines.

I am still not sure we need such an option. This option only changes an
address in arch/mips/include/asm/mach-loongson/loongson.h:

| #if defined(CONFIG_HT_PCI)
| #define LOONGSON_PCIIO_BASE     loongson_sysconf.pci_io_base
| #else
| #define LOONGSON_PCIIO_BASE     0x1fd00000
| #endif

If both options are working on a Loongson 3 machine, it's definitely a
good idea to leave the choice to the user. That said if only the address
from loongson_sysconf.pci_io_base works on a Loongson 3 machine, this
option must always be selected and is therefore useless.

> >  config PCI_DOMAINS
> >     bool
> >
> >diff --git a/arch/mips/loongson/Kconfig b/arch/mips/loongson/Kconfig
> >index 263beb9..4f3967c 100644
> >--- a/arch/mips/loongson/Kconfig
> >+++ b/arch/mips/loongson/Kconfig
> >@@ -59,6 +59,33 @@ config LEMOTE_MACH2F
> >
> >       These family machines include fuloong2f mini PC, yeeloong2f notebook,
> >       LingLoong allinone PC and so forth.
> >+
> >+config LEMOTE_MACH3A
> >+    bool "Lemote Loongson 3A family machines"
> >+    select ARCH_SPARSEMEM_ENABLE
> >+    select GENERIC_ISA_DMA_SUPPORT_BROKEN
> >+    select GENERIC_HARDIRQS_NO__DO_IRQ
> >+    select BOOT_ELF32
> >+    select BOARD_SCACHE
> >+    select CSRC_R4K
> >+    select CEVT_R4K
> >+    select CPU_HAS_WB
> >+    select HW_HAS_PCI
> >+    select ISA
> >+    select I8259
> >+    select IRQ_CPU
> >+    select SYS_HAS_CPU_LOONGSON3
> >+    select SYS_HAS_EARLY_PRINTK
> >+    select SYS_SUPPORTS_SMP
> >+    select SYS_SUPPORTS_64BIT_KERNEL
> >+    select SYS_SUPPORTS_HIGHMEM
> >+    select SYS_SUPPORTS_LITTLE_ENDIAN
> >+    select LOONGSON_MC146818
> >+    select ZONE_DMA32 if 64BIT
> >+    select LEFI_FIRMWARE_INTERFACE
> >+    help
> >+            Lemote Loongson 3A family machines utilize the 3A revision of
> >+            Loongson processor and RS780/SBX00 chipset.
> >  endchoice
> 
> Add "select NR_CPUS_DEFAULT_4" on here? Currently creating a
> configuration without using the loongson3_defconfig will default to
> 2, but unless I'm mistaken, all 3A machines are quad core?
> 
> >
> >  config CS5536
> >@@ -86,8 +114,24 @@ config LOONGSON_UART_BASE
> >     default y
> >     depends on EARLY_PRINTK || SERIAL_8250
> >
> >+config IOMMU_HELPER
> >+    bool
> >+
> >+config NEED_SG_DMA_LENGTH
> >+    bool
> >+
> >+config SWIOTLB
> >+    bool "Soft IOMMU Support for Big Memory (>4GB)"
> >+    depends on CPU_LOONGSON3
> >+    select IOMMU_HELPER
> >+    select NEED_SG_DMA_LENGTH
> >+    select NEED_DMA_MAP_STATE
> >+
> 
> Again, default to y?
> 
> Thanks,
> Alex
> 
> >  config LOONGSON_MC146818
> >     bool
> >     default n
> >
> >+config LEFI_FIRMWARE_INTERFACE
> >+    bool
> >+
> >  endif # MACH_LOONGSON
> >diff --git a/arch/mips/loongson/Platform b/arch/mips/loongson/Platform
> >index 29692e5..6205372 100644
> >--- a/arch/mips/loongson/Platform
> >+++ b/arch/mips/loongson/Platform
> >@@ -30,3 +30,4 @@ platform-$(CONFIG_MACH_LOONGSON) += loongson/
> >  cflags-$(CONFIG_MACH_LOONGSON) += 
> > -I$(srctree)/arch/mips/include/asm/mach-loongson -mno-branch-likely
> >  load-$(CONFIG_LEMOTE_FULOONG2E) += 0xffffffff80100000
> >  load-$(CONFIG_LEMOTE_MACH2F) += 0xffffffff80200000
> >+load-$(CONFIG_CPU_LOONGSON3) += 0xffffffff80200000
> >
> 
> 

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net

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