[PATCH 5.15 076/279] clk: at91: sama7g5: remove prescaler part of master clock

Greg Kroah-Hartman
2021-11-24T13:49:40Z

From: Claudiu Beznea <claudiu.beznea@microchip.com>

[ Upstream commit facb87ad75603813bc3b1314f5a87377f020fcb8 ]

On SAMA7G5 the prescaler part of master clock has been implemented as a
changeable one. Everytime the prescaler is changed the PMC_SR.MCKRDY bit
must be polled. Value 1 for PMC_SR.MCKRDY means the prescaler update is
done. Driver polls for this bit until it becomes 1. On SAMA7G5 it has
been discovered that in some conditions the PMC_SR.MCKRDY is not rising
but the rate it provides it's stable. The workaround is to add a timeout
when polling for PMC_SR.MCKRDY. At the moment, for SAMA7G5, the prescaler
will be removed from Linux clock tree as all the frequencies for CPU could
be obtained from PLL and also there will be less overhead when changing
frequency via DVFS.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20211011112719.3951784-14-claudiu.beznea@microchip.com
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/clk/at91/sama7g5.c | 11 +----------
1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/drivers/clk/at91/sama7g5.c b/drivers/clk/at91/sama7g5.c
index cf8c079aa086a..019e712f90d6f 100644
--- a/drivers/clk/at91/sama7g5.c
+++ b/drivers/clk/at91/sama7g5.c
@@ -982,16 +982,7 @@ static void __init sama7g5_pmc_setup(struct device_node *np)
}

parent_names[0] = "cpupll_divpmcck";
- hw = at91_clk_register_master_pres(regmap, "cpuck", 1, parent_names,
- &mck0_layout, &mck0_characteristics,
- &pmc_mck0_lock,
- CLK_SET_RATE_PARENT, 0);
- if (IS_ERR(hw))
- goto err_free;
-
- sama7g5_pmc->chws[PMC_CPU] = hw;
-
- hw = at91_clk_register_master_div(regmap, "mck0", "cpuck",
+ hw = at91_clk_register_master_div(regmap, "mck0", "cpupll_divpmcck",
&mck0_layout, &mck0_characteristics,
&pmc_mck0_lock, 0);
if (IS_ERR(hw))
--
2.33.0