diff mbox series

spi: pxa2xx: Apply CS clk quirk to BXT

Message ID 20200427163238.1.Ib1faaabe236e37ea73be9b8dcc6aa034cb3c8804@changeid
State New
Headers show
Series spi: pxa2xx: Apply CS clk quirk to BXT | expand

Commit Message

Evan Green April 27, 2020, 11:32 p.m. UTC
With a couple allies at Intel, and much badgering, I got confirmation
from Intel that at least BXT suffers from the same SPI chip-select
issue as Cannonlake (and beyond). The issue being that after going
through runtime suspend/resume, toggling the chip-select line without
also sending data does nothing.

Add the quirk to BXT to briefly toggle dynamic clock gating off and
on, forcing the fabric to wake up enough to notice the CS register
change.

Signed-off-by: Evan Green <evgreen@chromium.org>
Cc: Shobhit Srivastava <shobhit.srivastava@intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---

I don't actually have a BXT (Broxton/Apollolake?) system to test this.
To be honest I suspect the issue is there in older generations as well,
but I couldn't get Intel to confirm that, so this seemed like the
only safe change.
---
 drivers/spi/spi-pxa2xx.c | 1 +
 1 file changed, 1 insertion(+)
diff mbox series

Patch

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 73d2a65d0b6ef..20dcbd35611a7 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -150,6 +150,7 @@  static const struct lpss_config lpss_platforms[] = {
 		.tx_threshold_hi = 48,
 		.cs_sel_shift = 8,
 		.cs_sel_mask = 3 << 8,
+		.cs_clk_stays_gated = true,
 	},
 	{	/* LPSS_CNL_SSP */
 		.offset = 0x200,