From: jh80.chung@samsung•com (Jaehoon Chung)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCHv10 0/5] ARM: remove the sub-node and deprecate supports-highspeed property for dwmmc.
Date: Mon, 25 Aug 2014 21:11:51 +0900 [thread overview]
Message-ID: <53FB2807.7070503@samsung.com> (raw)
In-Reply-To: <53FB278B.7010509@samsung.com>
On 08/25/2014 09:09 PM, Jaehoon Chung wrote:
> On 08/25/2014 08:37 PM, Pavel Machek wrote:
>> On Mon 2014-08-25 20:28:21, Jaehoon Chung wrote:
>>> On 08/25/2014 08:21 PM, Pavel Machek wrote:
>>>> On Thu 2014-08-07 16:37:57, Jaehoon Chung wrote:
>>>>> Since used the mmc_of_parse(), didn't parse the sub-node.
>>>>> So we can remove the sub-node, because almost SoC used the only one card per a host.
>>>>> And supports-highspeed can be replaced with "cap-mmc/sd-highspeed"
>>>>> property.
>>>>
>>>> Would it be better to fix parsing of the device tree, and not to
>>>> change all the device trees?
>>>>
>>>> Someone will want to do two slots sooner or later...
>>>>
>>>
>>> First, I had considered that controller can be supported the multiple slot.
>>> But MMC maintainers and other people suggested that consider the only one card per a host.
>>> Two slots or more don't have any benefit, (power or performance, etc).
>>
>> Would you elaborate?
>>
>> If I have a device like a phone, I may want to put one "slot" inside
>> phone for basic system, and offer second slot for user expansion
>> (initially empty).
>
> if multiple slot is supported, then a mmcqd should be processing for multiple slots.
> It's too inefficient, and affect the whole performance reduction.
Sorry, Discard this comment. it means dwmci, not mmcqd.
>
> If want to offer the second slot for user expansion, add the host for expansion slot.
> Almost All SoC didn't use the multiple slot per a host controller for eMMC/SD/SDIO.
>
> If Some device(Phone) supports the SD-card and eMMC, then there are two Host IP.
> One Host IP is used for eMMC, other is used for SD-card.
>
> this is H/W design issue.
>
> a) You means the below,
>
> One Host IP -------- eMMC
> |
> ---- SD
> |
> ---- SDIO
>
> b) We means the below
> One Host IP -------- eMMC
> One Host IP -------- SD
> One Host IP -------- SDIO
>
> In now, I knew every SoC have used like b) type. I didn't see a) type (especially, dwmmc's case).
>
> If i missed something, let me know, plz.
>
> Best Regards,
> Jaehoon Chung
>
>>
>> Or I may want to have internal slot with a card to boot from and have
>> external slot (initially empty) for system update for embedded system.
>>
>> I see quite an obvious benefit there.
>> Pavel
>>
>
next prev parent reply other threads:[~2014-08-25 12:11 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-07 7:37 [PATCHv10 0/5] ARM: remove the sub-node and deprecate supports-highspeed property for dwmmc Jaehoon Chung
2014-08-07 7:37 ` [PATCHv10 1/5] mmc: dw_mmc: Slot quirk "disable-wp" is deprecated Jaehoon Chung
2014-08-11 9:45 ` Ulf Hansson
2014-08-07 7:37 ` [PATCHv10 2/5] mmc: dw_mmc: modify the dt-binding for removing slot-node and supports-highspeed Jaehoon Chung
2014-08-11 9:46 ` Ulf Hansson
2014-08-07 7:38 ` [PATCHv10 3/5] ARM: dts: exynos: unuse the slot-node and deprecate the supports-highspeed for dw-mmc Jaehoon Chung
2014-08-18 12:23 ` Jaehoon Chung
2014-08-18 14:10 ` Andreas Färber
2014-08-18 16:54 ` Kukjin Kim
2014-08-18 17:06 ` Andreas Färber
2014-08-18 17:40 ` Kukjin Kim
2014-08-19 3:52 ` Jaehoon Chung
2014-08-07 7:38 ` [PATCHv10 4/5] ARM: dts: socfpga: " Jaehoon Chung
2014-08-11 21:03 ` Dinh Nguyen
2014-08-07 7:38 ` [PATCHv10 5/5] ARM: dts: rockchip: " Jaehoon Chung
2014-08-11 14:38 ` Heiko Stübner
2014-08-25 11:21 ` [PATCHv10 0/5] ARM: remove the sub-node and deprecate supports-highspeed property for dwmmc Pavel Machek
2014-08-25 11:28 ` Jaehoon Chung
2014-08-25 11:37 ` Pavel Machek
2014-08-25 12:09 ` Jaehoon Chung
2014-08-25 12:11 ` Jaehoon Chung [this message]
2014-08-26 10:19 ` Pavel Machek
2014-08-27 3:11 ` Jaehoon Chung
2014-08-27 11:56 ` Pavel Machek
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