linux-kernel - [PATCH v1 5/7] soc: mediatek: add a fixed wait for SRAM stable

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Date:   Tue, 3 Apr 2018 15:15:55 +0800
From:   <sean.wang@...iatek.com>
To:     <robh+dt@...nel.org>, <mark.rutland@....com>,
        <marcel@...tmann.org>, <johan.hedberg@...il.com>
CC:     <devicetree@...r.kernel.org>, <linux-bluetooth@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, Sean Wang <sean.wang@...iatek.com>,
        "Matthias Brugger" <matthias.bgg@...il.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Weiyi Lu <weiyi.lu@...iatek.com>
Subject: [PATCH v1 5/7] soc: mediatek: add a fixed wait for SRAM stable

From: Sean Wang <sean.wang@...iatek.com>

MT7622_POWER_DOMAIN_WB doesn't send an ACK when its managed SRAM becomes
stable, which is not like the behavior the other power domains should
have. Therefore, it's necessary for such a power domain to have a fixed
and well-predefined duration to wait until its managed SRAM can be allowed
to access by all functions running on the top.

Signed-off-by: Sean Wang <sean.wang@...iatek.com>
Cc: Matthias Brugger <matthias.bgg@...il.com>
Cc: Ulf Hansson <ulf.hansson@...aro.org>
Cc: Weiyi Lu <weiyi.lu@...iatek.com>
---
 drivers/soc/mediatek/mtk-scpsys.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/soc/mediatek/mtk-scpsys.c b/drivers/soc/mediatek/mtk-scpsys.c
index f9b7248..19aceb8 100644
--- a/drivers/soc/mediatek/mtk-scpsys.c
+++ b/drivers/soc/mediatek/mtk-scpsys.c
@@ -121,6 +121,7 @@ struct scp_domain_data {
 	u32 bus_prot_mask;
 	enum clk_id clk_id[MAX_CLKS];
 	bool active_wakeup;
+	u32 us_sram_fwait;
 };
 
 struct scp;
@@ -234,11 +235,16 @@ static int scpsys_power_on(struct generic_pm_domain *genpd)
 	val &= ~scpd->data->sram_pdn_bits;
 	writel(val, ctl_addr);
 
-	/* wait until SRAM_PDN_ACK all 0 */
-	ret = readl_poll_timeout(ctl_addr, tmp, (tmp & pdn_ack) == 0,
-				 MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
-	if (ret < 0)
-		goto err_pwr_ack;
+	/* Either wait until SRAM_PDN_ACK all 0 or have a force wait */
+	if (!scpd->data->us_sram_fwait) {
+		ret = readl_poll_timeout(ctl_addr, tmp, (tmp & pdn_ack) == 0,
+					 MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
+		if (ret < 0)
+			goto err_pwr_ack;
+	} else {
+		usleep_range(scpd->data->us_sram_fwait,
+			     scpd->data->us_sram_fwait + 100);
+	};
 
 	if (scpd->data->bus_prot_mask) {
 		ret = mtk_infracfg_clear_bus_protection(scp->infracfg,
@@ -783,6 +789,7 @@ static const struct scp_domain_data scp_domain_data_mt7622[] = {
 		.clk_id = {CLK_NONE},
 		.bus_prot_mask = MT7622_TOP_AXI_PROT_EN_WB,
 		.active_wakeup = true,
+		.us_sram_fwait = 12000,
 	},
 };
 
-- 
2.7.4