[U-Boot] [PATCH] dm: mmc: socfpga: call dwmci_probe()

[Patrick Brünn]

>From: Patrick Brünn
>Sent: Donnerstag, 8. März 2018 06:39
>>From: Jaehoon Chung [mailto:jh80.chung at samsung.com]
>>Sent: Donnerstag, 8. März 2018 04:57
>>On 03/08/2018 12:12 PM, Marek Vasut wrote:
>>> On 03/08/2018 03:17 AM, Jaehoon Chung wrote:
>>>> On 03/06/2018 05:07 PM, linux-kernel-dev at beckhoff.com wrote:
>>>>> From: Patrick Bruenn <p.bruenn at beckhoff.com>
>>>>>
>>>>> On a socfpga_cyclone5 based board the SD card, was never powered
>up.
>>For
>>>>> other dw_mmc based SoCs dwmci_probe() is called in the platform
>>specific
>>>>> probe(). It seems this call is missing for socfpga_dw_mmc.
>>>>>
>>>>> With this change DWMCI_PWREN is set by dmwci_init().
>>>>>
>>>>> Signed-off-by: Patrick Bruenn <p.bruenn at beckhoff.com>
>>>>
>>>> Reviewed-by: Jaehoon Chung <jh80.chung at samsung.com>
>>>>
>>>> Will apply this patch before releasing v2018.03.
>>>> (I have a problem about accessing git.denx.de. After fixing my problem,
>>will resend email about applying.)
>>>
>>> DWMMC works on SoCFPGA for me (tested on rc4), so I don't understand
>>what this patch is trying to fix. I'd prefer if you did not hastily apply this.
>>
>>It's my misunderstanding. When i checked more. I think that Marek is right.
>>Thanks Marek for pointing out.
>>
>Okay, but do you have any hint what I am doing wrong? My board (cx8100 not
>mainline, yet) is based on socfpga_cyclone5. And on my board "
>dwmci_writel(host, DWMCI_PWREN, 1);" is never called, because
>dwmci_init() is never called.
>As far as I can see with CONFIG_DM_MMC enabled dwmci_init() should be
>called by dwmci_probe().
>
>exynos  and rockchip do call dwmci_probe() within
>exynos/rockchip_dwmmc_probe().
>but socfpga_dwmmc_probe() is missing this call. So I looked deeper but found
>no place for socfpga platform to call dwmci_probe() or dwmci_init().
>What am I missing?
>
I got an idea, what might be the difference between my board and your boards.
I suspect you use U-BOOT SPL without CONFIG_DM_MMC set, so
dwmci_init() is called indirectly by mmc_start_init().
Now, when your main U-Boot (with CONFIG_DM_MMC) is launched,
everything is already configured and it isn't necessary to call dwmci_init() again.
On my board the Altera MPL is used (and I can't replace it).  Which seems to
disable DWMCI_PWREN before launching U-Boot.
If my assumption is correct, I still think it is a U-Boot bug to assume code like in
dwmci_init() was already run before U-Boot gets in control.
Besides exynos/rockchip_dw_mmc don't have this precondition requirement.

Please take your time to look deeper into this issue, before deciding anything.
I don't think we need to rush this into the next release, as normal mainline
boards are "accidently" not affected.

Thanks and regards,
Patrick

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