Hi Geert,
Thanks for your work.
On 2020-01-15 14:13:23 +0100, Geert Uytterhoeven wrote:
> Add minimal runtime PM support (enable on probe, disable on remove), to
> ensure proper operation with a parent device that uses runtime PM.
>
> This is needed on systems where the FLASH is connected to a bus
> controller that is contained in a PM domain and/or has a gateable
> functional clock. In such cases, before accessing any device connected
> to the external bus, the PM domain must be powered up, and/or the
> functional clock must be enabled, which is typically handled through
> runtime PM by the bus controller driver.
>
> An example of this is the Renesas APE6-EVM development board, which has
> an Ethernet controller and a CFI FLASH connected to the Bus State
> Controller (BSC) of an R-Mobile APE6 SoC.
> As long as the Ethernet driver, which had Runtime PM support since
> commit 3a611e26e958b037 ("net/smsc911x: Add minimal runtime PM
> support"), keeps the BSC powered, accessing the FLASH works.
> When the ethernet node in r8a73a4-ape6evm.dts is disabled, the BSC is
> never powered up, and the kernel crashes when trying to access the
> FLASH:
>
> Unhandled fault: imprecise external abort (0x1406) at 0x00000000
> pgd = (ptrval)
> [00000000] *pgd=7fef2835
> Internal error: : 1406 [#1] SMP ARM
> CPU: 0 PID: 122 Comm: hd Tainted: G W 5.5.0-rc1-ape6evm-00814-g38ca966db25b9dbd-dirty #136
> Hardware name: Generic R8A73A4 (Flattened Device Tree)
> PC is at chip_ready+0x12c/0x380
> LR is at chip_ready+0x10c/0x380
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> ---
> Probably the device should be powered down after probing, and powered
> up/down on-demand in the various {get,put}_chip() functions. However,
> that is an optimization which touches more intimidate details of the
> internal MTD API, and can be done later.
> ---
> drivers/mtd/maps/physmap-core.c | 20 +++++++++++++++-----
> 1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/mtd/maps/physmap-core.c b/drivers/mtd/maps/physmap-core.c
> index a9f7964e2edb6668..8f7f966fa9a7ee8a 100644
> --- a/drivers/mtd/maps/physmap-core.c
> +++ b/drivers/mtd/maps/physmap-core.c
> @@ -38,6 +38,7 @@
> #include <linux/mtd/cfi_endian.h>
> #include <linux/io.h>
> #include <linux/of_device.h>
> +#include <linux/pm_runtime.h>
> #include <linux/gpio/consumer.h>
>
> #include "physmap-gemini.h"
> @@ -64,16 +65,16 @@ static int physmap_flash_remove(struct platform_device *dev)
> {
> struct physmap_flash_info *info;
> struct physmap_flash_data *physmap_data;
> - int i, err;
> + int i, err = 0;
>
> info = platform_get_drvdata(dev);
> if (!info)
> - return 0;
> + goto out;
>
> if (info->cmtd) {
> err = mtd_device_unregister(info->cmtd);
> if (err)
> - return err;
> + goto out;
>
> if (info->cmtd != info->mtds[0])
> mtd_concat_destroy(info->cmtd);
> @@ -88,7 +89,10 @@ static int physmap_flash_remove(struct platform_device *dev)
> if (physmap_data && physmap_data->exit)
> physmap_data->exit(dev);
>
> - return 0;
> +out:
> + pm_runtime_put(&dev->dev);
> + pm_runtime_disable(&dev->dev);
> + return err;
> }
>
> static void physmap_set_vpp(struct map_info *map, int state)
> @@ -484,13 +488,19 @@ static int physmap_flash_probe(struct platform_device *dev)
> return -EINVAL;
> }
>
> + pm_runtime_enable(&dev->dev);
> + pm_runtime_get_sync(&dev->dev);
> +
> if (dev->dev.of_node)
> err = physmap_flash_of_init(dev);
> else
> err = physmap_flash_pdata_init(dev);
>
> - if (err)
> + if (err) {
> + pm_runtime_put(&dev->dev);
> + pm_runtime_disable(&dev->dev);
> return err;
> + }
>
> for (i = 0; i < info->nmaps; i++) {
> struct resource *res;
> --
> 2.17.1
>
--
Regards,
Niklas Söderlund
