ARM: at91: pm: cpu_idle: switch DDR to power-down mode
On some DDR controllers, compatible with the sama5d3 one,
the sequence to enter/exit/re-enter the self-refresh mode adds
more constrains than what is currently written in the at91_idle
driver. An actual access to the DDR chip is needed between exit
and re-enter of this mode which is somehow difficult to implement.
This sequence can completely hang the SoC. It is particularly
experienced on parts which embed a L2 cache if the code run
between IDLE calls fits in it...
Moreover, as the intention is to enter and exit pretty rapidly
from IDLE, the power-down mode is a good candidate.
So now we use power-down instead of self-refresh. As we can
simplify the code for sama5d3 compatible DDR controllers,
we instantiate a new sama5d3_ddr_standby() function.
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: <stable@vger.kernel.org> # v4.1+
Fixes: 017b5522d5
("ARM: at91: Add new binding for sama5d3-ddramc")
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
This commit is contained in:
parent
9e10889a31
commit
60b89f1928
|
@ -289,6 +289,22 @@ static void at91_ddr_standby(void)
|
|||
at91_ramc_write(1, AT91_DDRSDRC_LPR, saved_lpr1);
|
||||
}
|
||||
|
||||
static void sama5d3_ddr_standby(void)
|
||||
{
|
||||
u32 lpr0;
|
||||
u32 saved_lpr0;
|
||||
|
||||
saved_lpr0 = at91_ramc_read(0, AT91_DDRSDRC_LPR);
|
||||
lpr0 = saved_lpr0 & ~AT91_DDRSDRC_LPCB;
|
||||
lpr0 |= AT91_DDRSDRC_LPCB_POWER_DOWN;
|
||||
|
||||
at91_ramc_write(0, AT91_DDRSDRC_LPR, lpr0);
|
||||
|
||||
cpu_do_idle();
|
||||
|
||||
at91_ramc_write(0, AT91_DDRSDRC_LPR, saved_lpr0);
|
||||
}
|
||||
|
||||
/* We manage both DDRAM/SDRAM controllers, we need more than one value to
|
||||
* remember.
|
||||
*/
|
||||
|
@ -323,7 +339,7 @@ static const struct of_device_id const ramc_ids[] __initconst = {
|
|||
{ .compatible = "atmel,at91rm9200-sdramc", .data = at91rm9200_standby },
|
||||
{ .compatible = "atmel,at91sam9260-sdramc", .data = at91sam9_sdram_standby },
|
||||
{ .compatible = "atmel,at91sam9g45-ddramc", .data = at91_ddr_standby },
|
||||
{ .compatible = "atmel,sama5d3-ddramc", .data = at91_ddr_standby },
|
||||
{ .compatible = "atmel,sama5d3-ddramc", .data = sama5d3_ddr_standby },
|
||||
{ /*sentinel*/ }
|
||||
};
|
||||
|
||||
|
|
Loading…
Reference in New Issue