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

[sean.wang]

From: Sean Wang <sean.w...@mediatek.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.w...@mediatek.com>
Cc: Matthias Brugger <matthias....@gmail.com>
Cc: Ulf Hansson <ulf.hans...@linaro.org>
Cc: Weiyi Lu <weiyi...@mediatek.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