diff options
| author | Guilherme G. Piccoli <gpiccoli@igalia.com> | 2022-07-19 22:53:17 +0300 |
|---|---|---|
| committer | Florian Fainelli <f.fainelli@gmail.com> | 2022-08-15 19:36:56 +0300 |
| commit | 751c3e19d0a354eebd5efad40003a22585ffd0bf (patch) | |
| tree | d4fc44deac6a130f2569c9aacafe2d26c7dc6888 | |
| parent | 568035b01cfb107af8d2e4bd2fb9aea22cf5b868 (diff) | |
| download | linux-751c3e19d0a354eebd5efad40003a22585ffd0bf.tar.xz | |
soc: bcm: brcmstb: Document panic notifier action and remove useless header
The panic notifier of this driver is very simple code-wise, just a
memory write to a special position with some numeric code. But this
is not clear from the semantic point-of-view, and there is no public
documentation about that either.
After discussing this in the mailing-lists [0] and having Florian
explained it very well, document that in the code for the future
generations asking the same questions. Also, while at it, remove
a useless header.
[0] https://lore.kernel.org/lkml/781cafb0-8d06-8b56-907a-5175c2da196a@gmail.com
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Doug Berger <opendmb@gmail.com>
Cc: Justin Chen <justinpopo6@gmail.com>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Markus Mayer <mmayer@broadcom.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Link: https://lore.kernel.org/r/20220719195325.402745-5-gpiccoli@igalia.com
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
| -rw-r--r-- | drivers/soc/bcm/brcmstb/pm/pm-arm.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/soc/bcm/brcmstb/pm/pm-arm.c b/drivers/soc/bcm/brcmstb/pm/pm-arm.c index d6b30d521307..7643c9ade888 100644 --- a/drivers/soc/bcm/brcmstb/pm/pm-arm.c +++ b/drivers/soc/bcm/brcmstb/pm/pm-arm.c @@ -25,7 +25,6 @@ #include <linux/kernel.h> #include <linux/memblock.h> #include <linux/module.h> -#include <linux/notifier.h> #include <linux/of.h> #include <linux/of_address.h> #include <linux/panic_notifier.h> @@ -664,7 +663,20 @@ static void __iomem *brcmstb_ioremap_match(const struct of_device_id *matches, return of_io_request_and_map(dn, index, dn->full_name); } - +/* + * The AON is a small domain in the SoC that can retain its state across + * various system wide sleep states and specific reset conditions; the + * AON DATA RAM is a small RAM of a few words (< 1KB) which can store + * persistent information across such events. + * + * The purpose of the below panic notifier is to help with notifying + * the bootloader that a panic occurred and so that it should try its + * best to preserve the DRAM contents holding that buffer for recovery + * by the kernel as opposed to wiping out DRAM clean again. + * + * Reference: comment from Florian Fainelli, at + * https://lore.kernel.org/lkml/781cafb0-8d06-8b56-907a-5175c2da196a@gmail.com + */ static int brcmstb_pm_panic_notify(struct notifier_block *nb, unsigned long action, void *data) { |