Hello!
Jaehoon Chung wrote:
> mmc core supported to hw_reset function.
> So i think we can use it. It's called at only initial time to clear the
> previous status.
> But i think it can be called at reboot time. (it needs to implement codes.)
> how about?
I don't think that's going the work. The problem here is that depending
on the board configuration, the eMMC might carry the bootloader. If the
eMMC subsystem is not properly reset _during_ reboot, the board won't
even start since no bootloader is found. So we don't even reach the
point where the kernel does anything.
With best wishes,
Tobias
>
> Best Regards,
> Jaehoon Chung
>
>>
>> Signed-off-by: Marek Szyprowski <m.szyprow...@samsung.com>
>> ---
>> .../devicetree/bindings/mmc/exynos-dw-mshc.txt | 6 +++
>> drivers/mmc/host/dw_mmc-exynos.c | 43
>> +++++++++++++++++++++-
>> 2 files changed, 48 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/mmc/exynos-dw-mshc.txt
>> b/Documentation/devicetree/bindings/mmc/exynos-dw-mshc.txt
>> index ee4fc0576c7d..fc53d335e7db 100644
>> --- a/Documentation/devicetree/bindings/mmc/exynos-dw-mshc.txt
>> +++ b/Documentation/devicetree/bindings/mmc/exynos-dw-mshc.txt
>> @@ -50,6 +50,12 @@ Required Properties:
>> - if CIU clock divider value is 0 (that is divide by 1), both tx and
>> rx
>> phase shift clocks should be 0.
>>
>> +Optional properties:
>> +
>> +* dw-mshc-reset-gpios: optional property specifying gpio for the eMMC nreset
>> + line, it will be triggered on system reboot to properly reset eMMC card
>> for
>> + next system boot.
>> +
>> Required properties for a slot (Deprecated - Recommend to use one slot per
>> host):
>>
>> * gpios: specifies a list of gpios used for command, clock and data bus. The
>> diff --git a/drivers/mmc/host/dw_mmc-exynos.c
>> b/drivers/mmc/host/dw_mmc-exynos.c
>> index 509365cb22c6..2add5a93859d 100644
>> --- a/drivers/mmc/host/dw_mmc-exynos.c
>> +++ b/drivers/mmc/host/dw_mmc-exynos.c
>> @@ -12,12 +12,14 @@
>> #include <linux/module.h>
>> #include <linux/platform_device.h>
>> #include <linux/clk.h>
>> +#include <linux/delay.h>
>> #include <linux/mmc/host.h>
>> #include <linux/mmc/dw_mmc.h>
>> #include <linux/mmc/mmc.h>
>> #include <linux/of.h>
>> #include <linux/of_gpio.h>
>> #include <linux/slab.h>
>> +#include <linux/reboot.h>
>>
>> #include "dw_mmc.h"
>> #include "dw_mmc-pltfm.h"
>> @@ -77,8 +79,23 @@ struct dw_mci_exynos_priv_data {
>> u32 sdr_timing;
>> u32 ddr_timing;
>> u32 cur_speed;
>> + struct gpio_desc *reset_gpio;
>> + struct notifier_block reset_nb;
>> };
>>
>> +static int dw_mci_restart_handler(struct notifier_block *this,
>> + unsigned long mode, void *cmd)
>> +{
>> + struct dw_mci_exynos_priv_data *data;
>> + data = container_of(this, struct dw_mci_exynos_priv_data, reset_nb);
>> +
>> + gpiod_direction_output(data->reset_gpio, 0);
>> + mdelay(150);
>> + gpiod_direction_output(data->reset_gpio, 1);
>> +
>> + return NOTIFY_DONE;
>> +}
>> +
>> static struct dw_mci_exynos_compatible {
>> char *compatible;
>> enum dw_mci_exynos_type ctrl_type;
>> @@ -295,7 +312,20 @@ static int dw_mci_exynos_parse_dt(struct dw_mci *host)
>> return ret;
>>
>> priv->ddr_timing = SDMMC_CLKSEL_TIMING(timing[0], timing[1], div);
>> +
>> + priv->reset_gpio = devm_gpiod_get_optional(host->dev,
>> + "samsung,dw-mshc-reset",
>> + GPIOD_OUT_HIGH);
>> + if (!IS_ERR_OR_NULL(priv->reset_gpio)) {
>> + priv->reset_nb.notifier_call = dw_mci_restart_handler;
>> + priv->reset_nb.priority = 255;
>> + ret = register_restart_handler(&priv->reset_nb);
>> + if (ret)
>> + dev_err(host->dev, "cannot register restart handler\n");
>> + }
>> +
>> host->priv = priv;
>> +
>> return 0;
>> }
>>
>> @@ -490,6 +520,17 @@ static int dw_mci_exynos_probe(struct platform_device
>> *pdev)
>> return dw_mci_pltfm_register(pdev, drv_data);
>> }
>>
>> +static int dw_mci_exynos_remove(struct platform_device *pdev)
>> +{
>> + struct dw_mci *host = platform_get_drvdata(pdev);
>> + struct dw_mci_exynos_priv_data *priv = host->priv;
>> +
>> + if (priv->reset_gpio)
>> + unregister_restart_handler(&priv->reset_nb);
>> +
>> + return dw_mci_pltfm_remove(pdev);
>> +}
>> +
>> static const struct dev_pm_ops dw_mci_exynos_pmops = {
>> SET_SYSTEM_SLEEP_PM_OPS(dw_mci_exynos_suspend, dw_mci_exynos_resume)
>> .resume_noirq = dw_mci_exynos_resume_noirq,
>> @@ -499,7 +540,7 @@ static const struct dev_pm_ops dw_mci_exynos_pmops = {
>>
>> static struct platform_driver dw_mci_exynos_pltfm_driver = {
>> .probe = dw_mci_exynos_probe,
>> - .remove = __exit_p(dw_mci_pltfm_remove),
>> + .remove = dw_mci_exynos_remove,
>> .driver = {
>> .name = "dwmmc_exynos",
>> .of_match_table = dw_mci_exynos_match,
>>
>
>
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