linux-kernel - Re: [PATCH 1/2] mmc: core: Improve marking broken HPI through devicetree

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Date:	Tue, 19 Apr 2016 11:42:03 +0200
From:	Olliver Schinagl <oliver@...inagl.nl>
To:	Ulf Hansson <ulf.hansson@...aro.org>
Cc:	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Chen-Yu Tsai <wens@...e.org>,
	Venu Byravarasu <vbyravarasu@...dia.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Michal Hocko <mhocko@...e.com>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Sudeep Holla <Sudeep.Holla@....com>,
	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	Wenkai Du <wenkai.du@...el.com>,
	Chaotian Jing <chaotian.jing@...iatek.com>,
	Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
	Hans de Goede <hdegoede@...hat.com>,
	Jaehoon Chung <jh80.chung@...sung.com>,
	Michal Suchanek <hramrach@...il.com>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/2] mmc: core: Improve marking broken HPI through
 devicetree

Hi Ulf,

On 19-04-16 11:29, Ulf Hansson wrote:
> On 19 April 2016 at 09:12, Olliver Schinagl <oliver@...inagl.nl> wrote:
>> In patch 81f8a7be66 Hans de Goede added a patch to allow marking an mmc
>> device as to having an broken HPI implementation. After talking some
>> with Hans, we now think it is actually the mmc controller that can be
>> broken and not support broken HPI's.
> I don't want us to invent a DT binding for something you *think* is a
> HW controller issue.
>
> Have you really excluded that this isn't a software issue? Me
> personally haven't been using HPI that much so I can't really tell
> about the code robustness from the mmc core (mmc protocol point of
> view).
Well this patch goes hand in hand so to speak with the broken-hpi patch 
introduced by him, he did most of the investigation. We just discussed 
how to handle it and asked me to cook up the patch.

@hans, what do you think?
>
> Kind regards
> Uffe
>
>> This patch adds a new capability, mmc-broken-hpi, which allows us to
>> mark a broken hpi implementation on the host level.
>>
>> Signed-off-by: Olliver Schinagl <oliver@...inagl.nl>
>> ---
>>   drivers/mmc/core/host.c  | 2 ++
>>   drivers/mmc/core/mmc.c   | 2 +-
>>   include/linux/mmc/host.h | 1 +
>>   3 files changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
>> index 6e4c55a..9b63b36 100644
>> --- a/drivers/mmc/core/host.c
>> +++ b/drivers/mmc/core/host.c
>> @@ -270,6 +270,8 @@ int mmc_of_parse(struct mmc_host *host)
>>                  host->caps |= MMC_CAP_HW_RESET;
>>          if (of_property_read_bool(np, "cap-sdio-irq"))
>>                  host->caps |= MMC_CAP_SDIO_IRQ;
>> +       if (of_property_read_bool(np, "mmc-broken-hpi"))
>> +               host->caps |= MMC_CAP_BROKEN_HPI;
>>          if (of_property_read_bool(np, "full-pwr-cycle"))
>>                  host->caps2 |= MMC_CAP2_FULL_PWR_CYCLE;
>>          if (of_property_read_bool(np, "keep-power-in-suspend"))
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index 4dbe3df..9a19562 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -1592,7 +1592,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
>>          /*
>>           * Enable HPI feature (if supported)
>>           */
>> -       if (card->ext_csd.hpi) {
>> +       if (card->ext_csd.hpi && !(host->caps & MMC_CAP_BROKEN_HPI)) {
>>                  err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
>>                                  EXT_CSD_HPI_MGMT, 1,
>>                                  card->ext_csd.generic_cmd6_time);
>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>> index 8dd4d29..20f758e 100644
>> --- a/include/linux/mmc/host.h
>> +++ b/include/linux/mmc/host.h
>> @@ -264,6 +264,7 @@ struct mmc_host {
>>   #define MMC_CAP_DRIVER_TYPE_A  (1 << 23)       /* Host supports Driver Type A */
>>   #define MMC_CAP_DRIVER_TYPE_C  (1 << 24)       /* Host supports Driver Type C */
>>   #define MMC_CAP_DRIVER_TYPE_D  (1 << 25)       /* Host supports Driver Type D */
>> +#define MMC_CAP_BROKEN_HPI     (1 << 29)       /* Host support for HPI is broken */
>>   #define MMC_CAP_CMD23          (1 << 30)       /* CMD23 supported. */
>>   #define MMC_CAP_HW_RESET       (1 << 31)       /* Hardware reset */
>>
>> --
>> 2.8.0.rc3
>>