Gregory, Arnd,
On Wed, Jan 08, 2014 at 04:06:27PM +0100, Gregory CLEMENT wrote:
> The first variants of Armada XP SoCs (A0 stepping) have issues related
> to the i2c controller which prevent to use the offload mechanism and
> lead to a kernel hang during boot.
>
> This commit add quirk in the mvebu platform code to check the SoC
> version and then update the compatible string for the i2c controller
> according to the revision of the SoC. Currently only some OpenBlocks
> AX3-4 boards are known to use an A0 revision so the check is done only
> for these boards.
>
> Signed-off-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> arch/arm/mach-mvebu/armada-370-xp.c | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/arch/arm/mach-mvebu/armada-370-xp.c b/arch/arm/mach-mvebu/armada-370-xp.c
> index e2acff98e750..0f61a4f22fb5 100644
> --- a/arch/arm/mach-mvebu/armada-370-xp.c
> +++ b/arch/arm/mach-mvebu/armada-370-xp.c
> @@ -21,6 +21,7 @@
> #include <linux/clocksource.h>
> #include <linux/dma-mapping.h>
> #include <linux/mbus.h>
> +#include <linux/slab.h>
> #include <asm/hardware/cache-l2x0.h>
> #include <asm/mach/arch.h>
> #include <asm/mach/map.h>
> @@ -28,6 +29,7 @@
> #include "armada-370-xp.h"
> #include "common.h"
> #include "coherency.h"
> +#include "mvebu-soc-id.h"
>
> static void __init armada_370_xp_map_io(void)
> {
> @@ -45,8 +47,38 @@ static void __init armada_370_xp_timer_and_clk_init(void)
> #endif
> }
>
> +static void __init i2c_quirk(void)
> +{
> + struct device_node *np;
> + u32 dev, rev;
> +
> + /*
> + * Only revisons more recent than A0 support the offload
> + * mechanism. We can exit only if we are sure that we can
> + * get the SoC revision and it is more recent than A0.
> + */
> + if (mvebu_get_soc_id(&rev, &dev) == 0 && dev > MV78XX0_A0_REV)
> + return;
> +
> + for_each_compatible_node(np, NULL, "marvell,mv78230-i2c") {
> + struct property *new_compat;
> +
> + new_compat = kzalloc(sizeof(*new_compat), GFP_KERNEL);
> +
> + new_compat->name = kstrdup("compatible", GFP_KERNEL);
> + new_compat->length = sizeof("marvell,mv78230-a0-i2c");
> + new_compat->value = kstrdup("marvell,mv78230-a0-i2c",
> + GFP_KERNEL);
I'm still having some trouble with this compatible string choice... But
I have refined the problem :)
Do we create new compatible strings to indicate errata, or to indicate
'from this version forward there are new features'? The former would
indicate as Gregory has written '...-a0-i2c', the latter would warrant
'...-b0-i2c' and disabling offloading if we don't see '...-b0-i2c'.
I can see Gregory's approach if he were still using the property
'offload-broken', but I suspect the compatible strings should be handled
differently.
thx,
Jason.
> +
> + of_update_property(np, new_compat);
> + }
> + return;
> +}
> +
> static void __init armada_370_xp_dt_init(void)
> {
> + if (of_machine_is_compatible("plathome,openblocks-ax3-4"))
> + i2c_quirk();
> of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
> }
>
> --
> 1.8.1.2
>
>
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