linux-kernel - Re: [PATCH v4 2/2] mmc: dw_mmc: add reset support to dwmmc host controller

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Date:	Fri, 12 Aug 2016 16:53:06 +0800
From:	Guodong Xu <guodong.xu@...aro.org>
To:	Jaehoon Chung <jh80.chung@...sung.com>
Cc:	Shawn Lin <shawn.lin@...k-chips.com>,
	Heiko Stübner <heiko@...ech.de>,
	Rob Herring <robh+dt@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	devicetree@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	linux-mmc@...r.kernel.org,
	Xinwei Kong <kong.kongxinwei@...ilicon.com>,
	Zhangfei Gao <zhangfei.gao@...aro.org>
Subject: Re: [PATCH v4 2/2] mmc: dw_mmc: add reset support to dwmmc host controller

On 11 August 2016 at 18:30, Jaehoon Chung <jh80.chung@...sung.com> wrote:
> Hi Guodong,
>
> On 08/11/2016 11:23 AM, Shawn Lin wrote:
>> On 2016/8/10 16:03, Guodong Xu wrote:
>>> Dwmmc host controller may in unknown state when entering kernel boot. One
>>> example is when booting from eMMC, bootloader need initialize MMC host
>>> controller into some state so it can read. In order to make sure MMC host
>>> controller in a clean initial state, this reset support is added.
>>>
>>> With this patch, a 'resets' property can be added into dw_mmc device
>>> tree node. The hardware logic is: dwmmc host controller IP receives a reset
>>> signal from a 'reset provider' (eg. power management unit). The 'resets'
>>> property points to this reset signal. So, during dwmmc driver probe,
>>> it can use this signal to reset itself.
>>>
>>> Refer to [1] for more information.
>>>
>>> [1] Documentation/devicetree/bindings/reset/reset.txt
>>>
>>> Signed-off-by: Guodong Xu <guodong.xu@...aro.org>
>>> Signed-off-by: Xinwei Kong <kong.kongxinwei@...ilicon.com>
>>> Signed-off-by: Zhangfei Gao <zhangfei.gao@...aro.org>
>>
>> Looks good to me,
>>
>> Reviewed-by: Shawn Lin <shawn.lin@...k-chips.com>
>
> Could you rebase on https://github.com/jh80chung/dw-mmc.git?
> Otherwise, when i apply your patch, i will rebase.
>

Sure, I rebased.
Sending v5.

-Guodong

> Best Regards,
> Jaehoon Chung
>
>>
>>> ---
>>>  drivers/mmc/host/dw_mmc.c  | 23 ++++++++++++++++++++++-
>>>  include/linux/mmc/dw_mmc.h |  2 ++
>>>  2 files changed, 24 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>>> index 32380d5..481d441 100644
>>> --- a/drivers/mmc/host/dw_mmc.c
>>> +++ b/drivers/mmc/host/dw_mmc.c
>>> @@ -2915,6 +2915,13 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
>>>      if (!pdata)
>>>          return ERR_PTR(-ENOMEM);
>>>
>>> +    /* find reset controller when exist */
>>> +    pdata->rstc = devm_reset_control_get_optional(dev, NULL);
>>> +    if (IS_ERR(pdata->rstc)) {
>>> +        if (PTR_ERR(pdata->rstc) == -EPROBE_DEFER)
>>> +            return ERR_PTR(-EPROBE_DEFER);
>>> +    }
>>> +
>>>      /* find out number of slots supported */
>>>      of_property_read_u32(np, "num-slots", &pdata->num_slots);
>>>
>>> @@ -2986,7 +2993,9 @@ int dw_mci_probe(struct dw_mci *host)
>>>
>>>      if (!host->pdata) {
>>>          host->pdata = dw_mci_parse_dt(host);
>>> -        if (IS_ERR(host->pdata)) {
>>> +        if (PTR_ERR(host->pdata) == -EPROBE_DEFER) {
>>> +            return -EPROBE_DEFER;
>>> +        } else if (IS_ERR(host->pdata)) {
>>>              dev_err(host->dev, "platform data not available\n");
>>>              return -EINVAL;
>>>          }
>>> @@ -3040,6 +3049,12 @@ int dw_mci_probe(struct dw_mci *host)
>>>          }
>>>      }
>>>
>>> +    if (!IS_ERR(host->pdata->rstc)) {
>>> +        reset_control_assert(host->pdata->rstc);
>>> +        usleep_range(10, 50);
>>> +        reset_control_deassert(host->pdata->rstc);
>>> +    }
>>> +
>>>      setup_timer(&host->cmd11_timer,
>>>              dw_mci_cmd11_timer, (unsigned long)host);
>>>
>>> @@ -3189,6 +3204,9 @@ err_dmaunmap:
>>>      if (host->use_dma && host->dma_ops->exit)
>>>          host->dma_ops->exit(host);
>>>
>>> +    if (!IS_ERR(host->pdata->rstc))
>>> +        reset_control_assert(host->pdata->rstc);
>>> +
>>>  err_clk_ciu:
>>>      if (!IS_ERR(host->ciu_clk))
>>>          clk_disable_unprepare(host->ciu_clk);
>>> @@ -3221,6 +3239,9 @@ void dw_mci_remove(struct dw_mci *host)
>>>      if (host->use_dma && host->dma_ops->exit)
>>>          host->dma_ops->exit(host);
>>>
>>> +    if (!IS_ERR(host->pdata->rstc))
>>> +        reset_control_assert(host->pdata->rstc);
>>> +
>>>      if (!IS_ERR(host->ciu_clk))
>>>          clk_disable_unprepare(host->ciu_clk);
>>>
>>> diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
>>> index 83b0edfc..f5af2bd 100644
>>> --- a/include/linux/mmc/dw_mmc.h
>>> +++ b/include/linux/mmc/dw_mmc.h
>>> @@ -17,6 +17,7 @@
>>>  #include <linux/scatterlist.h>
>>>  #include <linux/mmc/core.h>
>>>  #include <linux/dmaengine.h>
>>> +#include <linux/reset.h>
>>>
>>>  #define MAX_MCI_SLOTS    2
>>>
>>> @@ -259,6 +260,7 @@ struct dw_mci_board {
>>>      /* delay in mS before detecting cards after interrupt */
>>>      u32 detect_delay_ms;
>>>
>>> +    struct reset_control *rstc;
>>>      struct dw_mci_dma_ops *dma_ops;
>>>      struct dma_pdata *data;
>>>  };
>>>
>>
>>
>