On 03/29/2016 03:09 PM, Shawn Lin wrote: > 在 2016/3/29 13:56, Jaehoon Chung 写道: >> On 03/29/2016 11:22 AM, Shawn Lin wrote: >>> 在 2016/3/25 13:35, Guodong Xu 写道: >>>> Hi, Shawn >>>> >>>> Sorry I replied late. I added comments below. >>>> >>>> On 6 March 2016 at 22:16, Shawn Lin <shawn.lin@xxxxxxxxxxxxxx >>>> <mailto:shawn.lin@xxxxxxxxxxxxxx>> wrote: >>>> >>>> On 2016/3/6 16:47, Guodong Xu wrote: >>>> >>>> mmc registers may in abnormal state if mmc is used in bootloader, >>>> eg. to support booting from eMMC. So we need reset mmc registers >>>> when kernel boots up, instead of assuming mmc is in clean state. >>>> >>>> With this patch, user can add a 'resets' property into dw_mmc dts >>>> node. When driver parse_dt and probe, it calls reset API to >>>> deassert the 'reset' of dw_mmc host controller. When probe error or >>>> remove, it calls reset API to assert it. >>>> >>>> Please also refer to >>>> Documentation/devicetree/bindings/reset/reset.txt >>>> >>>> Signed-off-by: Guodong Xu <guodong.xu@xxxxxxxxxx >>>> <mailto:guodong.xu@xxxxxxxxxx>> >>>> Signed-off-by: Xinwei Kong <kong.kongxinwei@xxxxxxxxxxxxx >>>> <mailto:kong.kongxinwei@xxxxxxxxxxxxx>> >>>> Signed-off-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx >>>> <mailto:zhangfei.gao@xxxxxxxxxx>> >>>> >>>> >>>> Really should V2 and add the changelog. >>>> >>>> >>>> Yes, will do. next version I sent will be labelled as V3. >>>> >>>> >>>> >>>> --- >>>> drivers/mmc/host/dw_mmc.c | 22 +++++++++++++++++++++- >>>> 1 file changed, 21 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >>>> index 242f9a0..281ea9c 100644 >>>> --- a/drivers/mmc/host/dw_mmc.c >>>> +++ b/drivers/mmc/host/dw_mmc.c >>>> @@ -2878,6 +2878,14 @@ 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); >>>> + pdata->rstc = NULL; >>>> >>>> >>>> maybe we can remove "pdata->rstc = NULL", and directly >>>> use IS_ERR(..) for the following "if (host->pdata->rstc != NULL)" >>>> statement >>>> >>>> >>>> Yes, will do. >>>> I see your point, other lines in this file are using IS_ERR(!..), I will >>>> use this style too. >>>> >>>> + } >>>> + >>>> /* find out number of slots supported */ >>>> of_property_read_u32(np, "num-slots", &pdata->num_slots); >>>> >>>> @@ -2949,7 +2957,9 @@ 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; >>>> >>>> >>>> please fix the coding style here. >>>> >>>> >>>> Do you mean to add additional {} for this 'if' , like this? >>>> >>>> + if (PTR_ERR(host->pdata) == -EPROBE_DEFER) { >>>> + return -EPROBE_DEFER; >>>> >>>> + } >>>> >>>> I will add {}. >>>> >>>> >>>> >>>> + else if (IS_ERR(host->pdata)) { >>>> dev_err(host->dev, "platform data not >>>> available\n"); >>>> return -EINVAL; >>>> } >>>> @@ -3012,6 +3022,9 @@ int dw_mci_probe(struct dw_mci *host) >>>> } >>>> } >>>> >>>> + if (host->pdata->rstc != NULL) >>>> + reset_control_deassert(host->pdata->rstc); >>>> + >>>> >>>> >>>> sorry, I can't follow your intention here. Shouldn't it be something >>>> like "assert mmc -> may need delay -> deassert mmc". As your current >>>> code, nothing happend right? >>>> >>>> >>>> The chip exits from bootloader with this bit asserted. And when entering >>>> kernel, we only need to deassert. >>>> >>>> In my current code, the driver deassert mmc in _probe(), and assert mmc >>>> in _remove(). >>> >>> I catch your point. From the previous discussion, we add it to make sure >>> dw_mmc in good state after leaving bootloader to kernel. But My real question is that you can assert it in bootloader, so you can also >>> dessert it in bootloaer to make sure dw_mmc work fine when probing >>> in kernel. In that way, we don't need this patch? >> >> Doesn't dw_mci_hw_reset work fine? I think that card should be reset with MMC_CAP_HW_RESET. >> Could you check this? >> > > MMC_CAP_HW_RESET actually reset the mmc card, but Guodong means to > reset the controller rather than mmc card :) We have talked about FBE scenarios, right? :) Now, I remembered it. > > >> Best Regards, >> Jaehoon Chung >> >>> >>> More to think, Is it ok to match the behaviour of bootloader stage? >>> My bootloader doesn't assert the reset pin of dw_mmc, so it seams if >>> I want to fix you issue on kernel stage, I need a new round of >>> assert->delay->deassert. >>> >>> >>>> >>>> >>>> >>>> setup_timer(&host->cmd11_timer, >>>> dw_mci_cmd11_timer, (unsigned long)host); >>>> >>>> @@ -3164,6 +3177,9 @@ err_dmaunmap: >>>> if (host->use_dma && host->dma_ops->exit) >>>> host->dma_ops->exit(host); >>>> >>>> + if (host->pdata->rstc != NULL) >>>> + reset_control_assert(host->pdata->rstc); >>>> + >>>> err_clk_ciu: >>>> if (!IS_ERR(host->ciu_clk)) >>>> clk_disable_unprepare(host->ciu_clk); >>>> @@ -3196,11 +3212,15 @@ void dw_mci_remove(struct dw_mci *host) >>>> if (host->use_dma && host->dma_ops->exit) >>>> host->dma_ops->exit(host); >>>> >>>> + if (host->pdata->rstc != NULL) >>>> + reset_control_assert(host->pdata->rstc); >>>> + >>>> if (!IS_ERR(host->ciu_clk)) >>>> clk_disable_unprepare(host->ciu_clk); >>>> >>>> if (!IS_ERR(host->biu_clk)) >>>> clk_disable_unprepare(host->biu_clk); >>>> + >>>> } >>>> >>>> >>>> unnecessary new line here. >>>> >>>> >>>> Will fix. >>>> >>>> -Guodong >>>> >>>> >>>> EXPORT_SYMBOL(dw_mci_remove); >>>> >>>> >>>> >>>> >>>> -- >>>> Best Regards >>>> Shawn Lin >>>> >>>> >>> >>> >>> >> >> >> >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
