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Groups > linux.kernel > #1618251
| From | Alexandre Belloni <alexandre.belloni@free-electrons.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 4.4 23/26] power: reset: at91-poweroff: timely shutdown LPDDR memories |
| Date | 2017-04-06 20:20 +0200 |
| Message-ID | <ttkaJ-4pu-9@gated-at.bofh.it> (permalink) |
| References | <ttb7s-66T-19@gated-at.bofh.it> <ttc3x-6L0-51@gated-at.bofh.it> <ttjHI-3XQ-11@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 06/04/2017 at 18:45:39 +0100, Ben Hutchings wrote:
> On Thu, 2017-04-06 at 10:38 +0200, Greg Kroah-Hartman wrote:
> > 4.4-stable review patch. If anyone has any objections, please let me know.
> >
> > ------------------
> >
> > From: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> >
> > commit 0b0408745e7ff24757cbfd571d69026c0ddb803c upstream.
> >
> > LPDDR memories can only handle up to 400 uncontrolled power off. Ensure the
> > proper power off sequence is used before shutting down the platform.
> >
> > Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> > Signed-off-by: Sebastian Reichel <sre@kernel.org>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> [...]
> > +static void at91_lpddr_poweroff(void)
> > +{
> > + asm volatile(
> > + /* Align to cache lines */
> > + ".balign 32\n\t"
> > +
> > + /* Ensure AT91_SHDW_CR is in the TLB by reading it */
> > + " ldr r6, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
>
> This clobbers r6...
>
> > + /* Power down SDRAM0 */
> > + " str %1, [%0, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"
> > + /* Shutdown CPU */
> > + " str %3, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"
> > +
> > + " b .\n\t"
> > + :
> > + : "r" (mpddrc_base),
> > + "r" cpu_to_le32(AT91_DDRSDRC_LPDDR2_PWOFF),
> > + "r" (at91_shdwc_base),
> > + "r" cpu_to_le32(AT91_SHDW_KEY | AT91_SHDW_SHDW)
> > + : "r0");
> [...]
>
> ...but the clobber list has r0.
>
Indeed. However, It doesn't matter much as nothing can possibly run
afterwards.
--
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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[PATCH 4.4 23/26] power: reset: at91-poweroff: timely shutdown LPDDR memories Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-06 11:40 +0200
Re: [PATCH 4.4 23/26] power: reset: at91-poweroff: timely shutdown LPDDR memories Ben Hutchings <ben.hutchings@codethink.co.uk> - 2017-04-06 19:50 +0200
Re: [PATCH 4.4 23/26] power: reset: at91-poweroff: timely shutdown LPDDR memories Alexandre Belloni <alexandre.belloni@free-electrons.com> - 2017-04-06 20:20 +0200
Re: [PATCH 4.4 23/26] power: reset: at91-poweroff: timely shutdown LPDDR memories Ben Hutchings <ben.hutchings@codethink.co.uk> - 2017-04-06 20:30 +0200
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