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arm_mpam: Improve check for whether or not NRDY is hardware managed

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mpam_ris_hw_probe_csu_nrdy() sets and clears MSMON_CSU.NRDY and checks
whether it's configuration sticks. However, hardware isn't given a chance
to disagree. Based on rule LRTGP, in MPAM specification IHI0099 version
B.b, the hardware will set NRDY if it needs time to establish a count after
a configuration change.

Enable the monitor so that NRDY becomes relevant and change the
configuration after clearing NRDY to try and coax the hardware into setting
it.

Fixes: 8c90dc68a5 ("arm_mpam: Probe the hardware features resctrl supports")
Cc: <stable@vger.kernel.org>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ben Horgan 2026-05-07 16:28:14 +01:00 committed by Catalin Marinas
parent 4387970bbd
commit ccad6001be
1 changed files with 11 additions and 2 deletions
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13
drivers/resctrl/mpam_devices.c
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@ -730,8 +730,7 @@ static void mpam_enable_quirks(struct mpam_msc *msc)
*/
static bool mpam_ris_hw_probe_csu_nrdy(struct mpam_msc_ris *ris)
{
u32 now;
u32 mon_sel;
u32 now, mon_sel, ctl_val;
bool can_set, can_clear;
struct mpam_msc *msc = ris->vmsc->msc;
@ -742,11 +741,21 @@ static bool mpam_ris_hw_probe_csu_nrdy(struct mpam_msc_ris *ris)
FIELD_PREP(MSMON_CFG_MON_SEL_RIS, ris->ris_idx);
mpam_write_monsel_reg(msc, CFG_MON_SEL, mon_sel);
/* Hardware might ignore nrdy if it's not enabled */
ctl_val = MSMON_CFG_CSU_CTL_TYPE_CSU;
ctl_val |= MSMON_CFG_x_CTL_MATCH_PARTID;
ctl_val |= MSMON_CFG_x_CTL_MATCH_PMG;
ctl_val |= MSMON_CFG_x_CTL_EN;
mpam_write_monsel_reg(msc, CFG_CSU_FLT, 0);
mpam_write_monsel_reg(msc, CFG_CSU_CTL, ctl_val);
_mpam_write_monsel_reg(msc, MSMON_CSU, MSMON___NRDY);
now = _mpam_read_monsel_reg(msc, MSMON_CSU);
can_set = now & MSMON___NRDY;
_mpam_write_monsel_reg(msc, MSMON_CSU, 0);
/* Configuration change to try and coax hardware into setting nrdy */
mpam_write_monsel_reg(msc, CFG_CSU_FLT, 0x1);
now = _mpam_read_monsel_reg(msc, MSMON_CSU);
can_clear = !(now & MSMON___NRDY);
mpam_mon_sel_unlock(msc);