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

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Message-ID: <CAPDyKFqftYtrHvcQB7te1fuWxjWtrhOGY=5DnRTnrRxHm2cQ-A@mail.gmail.com>
Date:	Tue, 19 Apr 2016 11:29:28 +0200
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Olliver Schinagl <oliver@...inagl.nl>
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

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).

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
>