6.9-stable review patch. If anyone has any objections, please let me know.
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From: Matti Vaittinen mazziesaccount@gmail.com
[ Upstream commit 1ace99d7c7c4c801c0660246f741ff846a9b8e3c ]
The data-sheet for TPS6287x-Q1 https://www.ti.com/lit/ds/symlink/tps62873-q1.pdf states at chapter 9.3.6.1 Output Voltage Range:
"Note that every change to the VRANGE[1:0] bits must be followed by a write to the VSET register, even if the value of the VSET[7:0] bits does not change."
The current implementation of the driver uses the regulator_set_voltage_sel_pickable_regmap() helper which further uses regmap_update_bits() to write the VSET-register. The regmap_update_bits() will not access the hardware if the new register value is same as old. It is worth noting that this is true also when the register is marked volatile, which I can't say is wrong because 'read-mnodify-write'-cycle with a volatile register is in any case something user should carefully consider.
The 'range_applied_by_vsel'-flag in regulator desc was added to force the vsel register upodates by using regmap_write_bits(). This variant will always unconditionally write the bits to the hardware.
It is worth noting that the vsel is now forced to be written to the hardware, whether the range was changed or not. This may cause a performance drop if users are wrtiting same voltage value repeteadly.
It would be possible to read the range register to determine if it was changed, but this would be a performance issue for users who don't use reg cache for vsel.
Always write the VSET register to the hardware regardless the cache.
Signed-off-by: Matti Vaittinen mazziesaccount@gmail.com Fixes: 7b0518fbf2be ("regulator: Add support for TI TPS6287x regulators") Link: https://msgid.link/r/ZktD50C5twF1EuKu@fedora Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/regulator/tps6287x-regulator.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/regulator/tps6287x-regulator.c b/drivers/regulator/tps6287x-regulator.c index 9b7c3d77789e3..3c9d79e003e4b 100644 --- a/drivers/regulator/tps6287x-regulator.c +++ b/drivers/regulator/tps6287x-regulator.c @@ -115,6 +115,7 @@ static struct regulator_desc tps6287x_reg = { .vsel_mask = 0xFF, .vsel_range_reg = TPS6287X_CTRL2, .vsel_range_mask = TPS6287X_CTRL2_VRANGE, + .range_applied_by_vsel = true, .ramp_reg = TPS6287X_CTRL1, .ramp_mask = TPS6287X_CTRL1_VRAMP, .ramp_delay_table = tps6287x_ramp_table,