[PATCHv2 1/3] EDAC/altera: Use fast register IO for S10 IRQs

[thor.thayer@linux.intel.com]

From: Meng Li <Meng.Li@windriver.com>

When an irq occurs in altera edac driver, regmap_xxx() is invoked
in atomic context. Regmap must indicate register IO is fast so
that a spinlock is used instead of a mutex to avoid sleeping
in atomic context.

Fixes mutex-lock error
   lock_acquire+0xfc/0x288
   __mutex_lock+0x8c/0x808
   mutex_lock_nested+0x3c/0x50
   regmap_lock_mutex+0x24/0x30
   regmap_write+0x40/0x78
   a10_eccmgr_irq_unmask+0x34/0x40
   unmask_irq.part.0+0x30/0x50
   irq_enable+0x74/0x80
   __irq_startup+0x80/0xa8
   irq_startup+0x70/0x150
   __setup_irq+0x650/0x6d0
   request_threaded_irq+0xe4/0x180
   devm_request_threaded_irq+0x7c/0xf0
   altr_sdram_probe+0x2c4/0x600
<snip>

Upstream fix pending [1] (common code uses fast mode)
[1] https://lkml.org/lkml/2019/11/7/1014

Fixes: 3dab6bd52687 ("EDAC, altera: Add support for Stratix10 SDRAM EDAC")
Cc: stable@vger.kernel.org
Reported-by: Meng Li <Meng.Li@windriver.com>
Signed-off-by: Meng Li <Meng.Li@windriver.com>
Reviewed-by: Thor Thayer <thor.thayer@linux.intel.com>
---
v2 Change Author to Meng Li & Reviewed-by: Thor Thayer
---
 drivers/edac/altera_edac.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/edac/altera_edac.c b/drivers/edac/altera_edac.c
index fbda4b876afd..0be3d1b17f03 100644
--- a/drivers/edac/altera_edac.c
+++ b/drivers/edac/altera_edac.c
@@ -560,6 +560,7 @@ static const struct regmap_config s10_sdram_regmap_cfg = {
 	.reg_write = s10_protected_reg_write,
 	.use_single_read = true,
 	.use_single_write = true,
+	.fast_io = true,
 };
 
 /************** </Stratix10 EDAC Memory Controller Functions> ***********/
-- 
2.7.4