linux-kernel - Re: [PATCH v3] mmc: dw_mmc: add quirk for broken data transfer over scheme

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Date:	Tue, 2 Dec 2014 21:08:57 -0800
From:	Doug Anderson <dianders@...omium.org>
To:	Addy Ke <addy.ke@...k-chips.com>
Cc:	Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	Seungwon Jeon <tgih.jun@...sung.com>,
	Jaehoon Chung <jh80.chung@...sung.com>,
	Chris Ball <chris@...ntf.net>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Dinh Nguyen <dinguyen@...era.com>,
	Heiko Stübner <heiko@...ech.de>,
	Olof Johansson <olof@...om.net>,
	Sonny Rao <sonnyrao@...omium.org>,
	Alexandru Stan <amstan@...omium.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
	"zhenfu.fang" <zhenfu.fang@...k-chips.com>,
	Eddie Cai <cf@...k-chips.com>, lintao <lintao@...k-chips.com>,
	chenfen <chenfen@...k-chips.com>, zyf <zyf@...k-chips.com>,
	Jianqun Xu <xjq@...k-chips.com>,
	Tao Huang <huangtao@...k-chips.com>,
	Chris <zyw@...k-chips.com>,
	姚智情 <yzq@...k-chips.com>,
	han jiang <hj@...k-chips.com>,
	Kever Yang <kever.yang@...k-chips.com>,
	zhangqing <zhangqing@...k-chips.com>,
	Lin Huang <hl@...k-chips.com>
Subject: Re: [PATCH v3] mmc: dw_mmc: add quirk for broken data transfer over scheme

Addy,

On Tue, Dec 2, 2014 at 7:16 PM, Addy Ke <addy.ke@...k-chips.com> wrote:
> This patch add a new quirk to add a s/w timer to notify the driver
> to terminate current transfer and report a data timeout to the core,
> if DTO interrupt does NOT come within the given time.
>
> dw_mmc call mmc_request_done func to finish transfer depends on
> DTO interrupt. If DTO interrupt does not come in sending data state,
> the current transfer will be blocked.
>
> But this case really exists, when driver reads tuning data from
> card on RK3288-pink2 board. I measured waveforms by oscilloscope
> and found that card clock was always on and data lines were always
> holded high level in sending data state.
>
> We got the reply from synopsys:
> There are two counters but both use the same value of [31:8] bits.
> Data timeout counter doesn't wait for stop clock and you should get
> DRTO even when the clock is not stopped.
> Host Starvation timeout counter is triggered with stop clock condition.
>
> This means that host should get DRTO and DTO interrupt.
>
> But we really don't get any data-related interrupt in RK3X SoCs.
> And driver can't get data transfer state, it can do nothing but wait for.
>
> We don't know why we have this problem, but we need it to fix this problem now.
> And I will post a follow up change when we find the root cause.
>
> Signed-off-by: Addy Ke <addy.ke@...k-chips.com>
> ---
> Changes in v2:
> - fix some typo.
> - remove extra timeout value (250ms).
> - remove dw_mci_dto_start_monitor func.
> - use "broken-dto" for new quirk and change Subject for it.
>
> Changes in v3:
> - Remove dts for broken-dto, just add this quirk in dw_mci_rockchip_init
>
>  drivers/mmc/host/dw_mmc-rockchip.c |  3 +++
>  drivers/mmc/host/dw_mmc.c          | 41 +++++++++++++++++++++++++++++++++++++-
>  include/linux/mmc/dw_mmc.h         |  5 +++++
>  3 files changed, 48 insertions(+), 1 deletion(-)

This seems reasonable to me.  I do hope that you can get to a root
cause, but I don't think this is a terrible bit of code to carry.
Obviously it's up to the folks who maintain dw_mmc and the mmc
subsystem, but:

Reviewed-by: Doug Anderson <dianders@...omium.org>
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