[PATCHv10 0/5] ARM: remove the sub-node and deprecate supports-highspeed property for dwmmc.

[Jaehoon Chung]

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
>>
>