On 05/06/2015 12:21 PM, Jaehoon Chung wrote:
Hi, Zhangfei.
On 05/06/2015 11:16 AM, zhangfei wrote:
On 05/06/2015 09:39 AM, Jaehoon Chung wrote:
Hi,
On 05/06/2015 10:33 AM, zhangfei wrote:
On 05/06/2015 09:26 AM, Jaehoon Chung wrote:
Hi,
On 05/06/2015 10:14 AM, Zhangfei Gao wrote:
On 6 May 2015 at 08:36, Jaehoon Chung <jh80.chung@xxxxxxxxxxx> wrote:
Hi, Zhangfei.
If you want to check it, use the "broken-cd" and "non-removable" properties into dt-file.
Did you use them?
Yes.
"broken-cd" can work, but mmc_rescan keeps running.
"non-removable" does NOT work, which should be used for emmc.
Since dw_mci_get_cd only checks DW_MCI_QUIRK_BROKEN_CARD_DETECTION, so
only checks "broken-cd" but not check "non-removable"
Did you use the usage like the below..
dwmmc0 {
non-removable;
broken-cd;
};
non-removable and broken-cd should be used only one.
Did you check the code?
If non-removable is set, broken-cd should be discarded.
I think that the below usage is not "must not".
I understand you meaning, you suggest
dwmmc0 {
non-removable;
broken-cd;
};
drivers/mmc/host/dw_mmc.c checks broken-cd, while mmc_of_parse checks non-removable.
Yes, it works.
But is it a workaround? and a little tricky.
It costs me some time to find why non-removable does not work, someone else may meet the same issue.
It does not align with Documentation/devicetree/bindings/mmc/mmc.txt, which is the guideline to write dts.
And see drivers/mmc/host/sdhci.c: sdhci_do_get_cd, it also checks both.
"non-removable" is assumed that card is not removed.
it's not also correct detect scheme. Then it's also able to say the broken card detection scheme.
(if CDETECT register can't use.)
BROKEN_CARD_DETECTION quirk means that it has unreliable card detection.
When dw-mmc host controller has unreliable card detection scheme, it could be set.
Is this tricky? i don't think so.
Though non-removable doesn't set, it has to work fine, isn't?
If non-removable is not set, broken-cd has to be set.
Or set both, but usually we may not consider this at first.
When we first want to enable emmc, we naturally use non-removable,
according to Documentation/devicetree/bindings/mmc/mmc.txt
Only one of the properties in this section should be supplied:
- broken-cd: There is no card detection available; polling must be used.
- cd-gpios: Specify GPIOs for card detection, see gpio binding
- non-removable: non-removable slot (like eMMC); assume always present.
But unfortunately we find it does not work and took half day to debug,
happen to find broken-cd can work, though mmc_rescan is keeps running
for a while, and we treat it as workaround.
After some time, another person find broken-cd does not make sense, and
debug again about non-removable, and took another half day.
It really happens here :(
So is it better support just using non-removable for emmc, aligning with
mmc.txt.
And i don't think that dw-mmc controller must use it since sdhci controller used.
(I have known that sdhci controller is using that.)
Well, If Ulf thinks this is tricky, i will consider this patch.
Thanks
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