4.14-stable review patch. If anyone has any objections, please let me know.
------------------ From: NeilBrown <[email protected]> commit a63d706ea719190a79a6c769e898f70680044d3e upstream. Since commit 3af5a67c86a3 ("MIPS: Fix early CM probing") the MT7621 has not been able to boot. This commit caused mips_cm_probe() to be called before mt7621.c::proc_soc_init(). prom_soc_init() has a comment explaining that mips_cm_probe() "wipes out the bootloader config" and means that configuration registers are no longer available. It has some code to re-enable this config. Before this re-enable code is run, the sysc register cannot be read, so when SYSC_REG_CHIP_NAME0 is read, a garbage value is returned and panic() is called. If we move the config-repair code to the top of prom_soc_init(), the registers can be read and boot can proceed. Very occasionally, the first register read after the reconfiguration returns garbage, so add a call to __sync(). Fixes: 3af5a67c86a3 ("MIPS: Fix early CM probing") Signed-off-by: NeilBrown <[email protected]> Reviewed-by: Matt Redfearn <[email protected]> Cc: John Crispin <[email protected]> Cc: Ralf Baechle <[email protected]> Cc: [email protected] Cc: <[email protected]> # 4.5+ Patchwork: https://patchwork.linux-mips.org/patch/18859/ Signed-off-by: James Hogan <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/mips/ralink/mt7621.c | 42 ++++++++++++++++++++++-------------------- 1 file changed, 22 insertions(+), 20 deletions(-) --- a/arch/mips/ralink/mt7621.c +++ b/arch/mips/ralink/mt7621.c @@ -170,6 +170,28 @@ void prom_soc_init(struct ralink_soc_inf u32 n1; u32 rev; + /* Early detection of CMP support */ + mips_cm_probe(); + mips_cpc_probe(); + + if (mips_cps_numiocu(0)) { + /* + * mips_cm_probe() wipes out bootloader + * config for CM regions and we have to configure them + * again. This SoC cannot talk to pamlbus devices + * witout proper iocu region set up. + * + * FIXME: it would be better to do this with values + * from DT, but we need this very early because + * without this we cannot talk to pretty much anything + * including serial. + */ + write_gcr_reg0_base(MT7621_PALMBUS_BASE); + write_gcr_reg0_mask(~MT7621_PALMBUS_SIZE | + CM_GCR_REGn_MASK_CMTGT_IOCU0); + __sync(); + } + n0 = __raw_readl(sysc + SYSC_REG_CHIP_NAME0); n1 = __raw_readl(sysc + SYSC_REG_CHIP_NAME1); @@ -194,26 +216,6 @@ void prom_soc_init(struct ralink_soc_inf rt2880_pinmux_data = mt7621_pinmux_data; - /* Early detection of CMP support */ - mips_cm_probe(); - mips_cpc_probe(); - - if (mips_cps_numiocu(0)) { - /* - * mips_cm_probe() wipes out bootloader - * config for CM regions and we have to configure them - * again. This SoC cannot talk to pamlbus devices - * witout proper iocu region set up. - * - * FIXME: it would be better to do this with values - * from DT, but we need this very early because - * without this we cannot talk to pretty much anything - * including serial. - */ - write_gcr_reg0_base(MT7621_PALMBUS_BASE); - write_gcr_reg0_mask(~MT7621_PALMBUS_SIZE | - CM_GCR_REGn_MASK_CMTGT_IOCU0); - } if (!register_cps_smp_ops()) return;
