linux-kernel - [PATCH AUTOSEL 5.4 017/175] spi: pxa2xx: Apply CS clk quirk to BXT

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Message-Id: <20200608231848.3366970-17-sashal@kernel.org>
Date:   Mon,  8 Jun 2020 19:16:10 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Evan Green <evgreen@...omium.org>,
        Shobhit Srivastava <shobhit.srivastava@...el.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mark Brown <broonie@...nel.org>,
        Sasha Levin <sashal@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-spi@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 017/175] spi: pxa2xx: Apply CS clk quirk to BXT

From: Evan Green <evgreen@...omium.org>

[ Upstream commit 6eefaee4f2d366a389da0eb95e524ba82bf358c4 ]

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@...omium.org>
Cc: Shobhit Srivastava <shobhit.srivastava@...el.com>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Link: https://lore.kernel.org/r/20200427163238.1.Ib1faaabe236e37ea73be9b8dcc6aa034cb3c8804@changeid
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/spi/spi-pxa2xx.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 723145673206..36b837fc7e4b 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -148,6 +148,7 @@ 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,
-- 
2.25.1