Dear, Doug. On 10/23/2014 01:36 AM, Doug Anderson wrote: > Hi, > > On Sun, Oct 19, 2014 at 8:23 PM, Jaehoon Chung <jh80.ch...@samsung.com> wrote: >> Hi. >> >> On 10/17/2014 09:44 PM, Alim Akhtar wrote: >>> Hi Doug, >>> >>> On Thu, Oct 16, 2014 at 9:40 PM, Doug Anderson <diand...@chromium.org> >>> wrote: >>>> Alim, >>>> >>>> On Thu, Oct 16, 2014 at 5:57 AM, Alim Akhtar <alim.akh...@gmail.com> wrote: >>>>> Hi Doug, >>>>> >>>>> On Tue, Oct 14, 2014 at 10:03 PM, Doug Anderson <diand...@chromium.org> >>>>> wrote: >>>>>> The dw_mmc driver had a bunch of code that ran whenever a card was >>>>>> ejected and inserted. However, this code was old and crufty and >>>>>> should be removed. Some evidence that it's really not needed: >>>>>> >>>>>> 1. Is is supposed to be legal to use 'cd-gpio' on dw_mmc instead of >>>>>> using the built-in card detect mechanism. The 'cd-gpio' code >>>>>> doesn't run any of the crufty old code but yet still works. >>>>>> >>>>>> 2. While looking at this, I realized that my old change (369ac86 mmc: >>>>>> dw_mmc: don't queue up a card detect at slot startup) actually >>>>>> castrated the old code a little bit already and nobody noticed. >>>>>> Specifically "last_detect_state" was left as 0 at bootup. That >>>>>> means that on the first card removal none of the crufty code ran. >>>>>> >>>>> Yes, right most of these codes are _almost_ never call. But I see >>>>> dw_mci_reset() being called on card removal (after first >>>>> insert/removal). >>>> >>>> Right. The old crufty code was called on the 2nd removal, not the >>>> 1st. That meant that the two were accidentally different. My point >>>> was that if the old code was really required that someone would have >>>> noticed crashes on the 1st removal after each boot. Since nobody is >>>> reporting crashes with that then it means it can't be too terrible. >>>> >>>> One thing to note: I remember in the last Chromebook project you were >>>> trying to track down crashes associated with constant eject / insert >>>> of SD Cards. I wonder if my patch will fix these crashes? >>>> >>> Ah, yes, reproducing that and checking with this patch will be really >>> interesting. >>> >>>> >>>>> I tested this on exynos5800 and this looks working fine. We need to >>>>> test once cross suspend/resume as well. >>>> >>>> Good idea. Can you test that? I know that there's been lots of flux >>>> with suspend/resume on exynos and I'm not sure I have all the latest >>>> patches, but I'll search for them if you are unable to test easily. >>>> >>> Sure, I will do that..but probably sometime next week, as I will out >>> of office for few days. >>>> >>>>> And as Jaehoon pointed out,probably lets look in TRM if there are some >>>>> recommended steps for cd-detect. >>>>> Otherwise this looks good to me. >>>> >>>> If you see some other requirement than the one I addressed in my email >>>> to Jaehoon, please let me know. >> >> I know there is no other requirement for detecting card. >> So this patch can be applied after testing the above case(suspend/resume). > > I put a kernel based upon 3.17 on an exynos5250-snow (specifically > git://git.collabora.co.uk/git/user/javier/linux.git branch > max77802-op-modes-v3, git hash 98cf5a0). Snow uses the builtin card > detect on dw_mmc. Resume wasn't terribly reliable to start with even > without my patch (it often woke up right after suspend), but it worked > well enough for testing. I tested the following scenarios: > > 1. Leave card in and mounted. Suspend/resume. Card is still usable > after resume > > 2. Suspend and insert card. Resume. Card is detected upon resume. > > 3. Suspend and remove card. Resume. Card is removed upon resume. > > How does that sound?
I think these test cases are enough, and if it's working fine, sounds good. Acked-by: Jaehoon Chung <jh80.ch...@samsung.com> Best Regards, Jaehoon Chung > > -Doug > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
