Messages in this thread | | | Date | Tue, 18 Oct 2022 14:16:58 +0100 | From | Paul Cercueil <> | Subject | Re: [PATCH v2 2/2] dmaengine: JZ4780: Add support for the JZ4755. |
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Hi,
Le lun., oct. 17 2022 at 20:29:27 +0300, Siarhei Volkau <lis8215@gmail.com> a écrit : > пн, 17 окт. 2022 г. в 12:34, Paul Cercueil > <paul@crapouillou.net>: >> Can you verify that? >> >> It should be pretty simple, if it has the bug you'll see I/O errors >> on >> the SD card. > > Well, the result is ambiguous: > > Without that 'broken' flag: mmc works poorly, but becomes more or less > stable when MMC clock downs to 6MHz (90% boots without errors). > On the 12MHz MMC clock the issue doesn't appear in 50-70% cases. > On the 24MHz MMC clock the device never boots up. > > However with the flag: MMC works stable on 24MHz MMC clock > (boot issue observed only once), but if I increase MMC clock speed > even > a bit the problem appears oftenly ( >70% of cases). > > So, that flag definitely helps a lot, but the nature of the problem > might be > different.
If the flag makes any difference then it's needed.
The controller should support up to 50 MHz, make sure that your "mmc" clock is at 50 MHz otherwise changing the max-frequency DT property won't do much.
Cheers, -Paul
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