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<0963b60f-15e7-4bc6-10df-6fc8003e4d42@nvidia.com> <34fd84d7-387b-b6f3-7fb3-aa490909e205@ti.com> <5e9b5646-bd48-e55b-54ee-1c2c41fc9218@nvidia.com> <757853cf-987e-f6b6-9259-b4560a031692@nvidia.com>

<87ad7586-9569-4276-044a-adb64e84ca15@nvidia.com> Message-ID: <57ddddc2-3ee8-d867-bba0-0dd9929ba37d@nvidia.com> Date: Wed, 4 Mar 2020 16:20:28 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Content-Language: en-US DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1583367577; bh=PvVpCnIN3EwQwvxNgWZ4rOeiZyAil49YWdcFT/wymLk=; h=X-PGP-Universal:Subject:From:To:CC:References:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Transfer-Encoding: Content-Language; b=VK1FsfNLDgRxRM8KppHOL6VF0MSHLNQ+BdiRK+DUHGdJ4o7zoqW9Wu2x5vSkA62EP zcaO1gFsYYOnPCEeXNO/LWC8cQeAqJangh/aD7ULRFzopQkxZaEeRvJxryRLzD7T6y xv0CTVVTyIR2IE1/H7hXdgaS1o9kj6Iyj5MEKiS7S3serr+lepAijqeVPjFVb72IfI MtKoiKYi3GKOzz3agtOOEfXktr8lgK5C9Z+V/wQy0vouRU84mj/fdrHgyHePKXdEYH ndszPirmNnGxOxbWZkbVYt2Tc5S98QRhXC6a2j4NYRGC4lgIKI6Yh7Xf9qHJBoHAlX EOQ+ZssSvyP6g== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/4/20 2:35 PM, Sowjanya Komatineni wrote: > > On 3/4/20 9:51 AM, Sowjanya Komatineni wrote: >> >> On 3/4/20 9:26 AM, Sowjanya Komatineni wrote: >>> >>> On 3/4/20 9:21 AM, Sowjanya Komatineni wrote: >>>> >>>> On 3/4/20 8:56 AM, Sowjanya Komatineni wrote: >>>>> >>>>> On 3/4/20 2:18 AM, Ulf Hansson wrote: >>>>>> External email: Use caution opening links or attachments >>>>>> >>>>>> >>>>>> [...] >>>>>> >>>>>>> So, from my side, me and Anders Roxell, have been collaborating on >>>>>>> testing the behaviour on a TI Beagleboard x15 (remotely with=20 >>>>>>> limited >>>>>>> debug options), which is using the sdhci-omap variant. I am=20 >>>>>>> trying to >>>>>>> get hold of an Nvidia jetson-TX2, but not found one yet. These=20 >>>>>>> are the >>>>>>> conclusions from the observed behaviour on the Beagleboard for the >>>>>>> CMD6 cache flush command. >>>>>>> >>>>>>> First, the reported host->max_busy_timeout is 2581 (ms) for the >>>>>>> sdhci-omap driver in this configuration. >>>>>>> >>>>>>> 1. As we all know by now, the cache flush command (CMD6) fails with >>>>>>> -110 currently. This is when MMC_CACHE_FLUSH_TIMEOUT_MS is set=20 >>>>>>> to 30 * >>>>>>> 1000 (30s), which means __mmc_switch() drops the MMC_RSP_BUSY flag >>>>>>> from the command. >>>>>>> >>>>>>> 2. Changing the MMC_CACHE_FLUSH_TIMEOUT_MS to 2000 (2s), means that >>>>>>> the MMC_RSP_BUSY flag becomes set by __mmc_switch, because of the >>>>>>> timeout_ms parameter is less than max_busy_timeout (2000 < 2581). >>>>>>> Then everything works fine. >>>>>>> >>>>>>> 3. Updating the code to again use 30s as the >>>>>>> MMC_CACHE_FLUSH_TIMEOUT_MS, but instead forcing the MMC_RSP_BUSY=20 >>>>>>> to be >>>>>>> set, even when the timeout_ms becomes greater than=20 >>>>>>> max_busy_timeout. >>>>>>> This also works fine. >>>>>>> >>>>>>> Clearly this indicates a problem that I think needs to be=20 >>>>>>> addressed in >>>>>>> the sdhci driver. However, of course I can revert the three=20 >>>>>>> discussed >>>>>>> patches to fix the problem, but that would only hide the issues=20 >>>>>>> and I >>>>>>> am sure we would then get back to this issue, sooner or later. >>>>>>> >>>>>>> To fix the problem in the sdhci driver, I would appreciate if=20 >>>>>>> someone >>>>>>> from TI and Nvidia can step in to help, as I don't have the HW=20 >>>>>>> on my >>>>>>> desk. >>>>>>> >>>>>>> Comments or other ideas of how to move forward? >>>>>> [...] >>>>>> >>>>>>> Hi Ulf, >>>>>>> >>>>>>> I could repro during suspend on Jetson TX1/TX2 as when it does=20 >>>>>>> mmc flush cache. >>>>>> Okay, great. >>>>>> >>>>>>> >>>>>>> Timeout I see is for switch status CMD13 after sending CMD6 as=20 >>>>>>> device side CMD6 is still inflight while host sends CMD13 as we=20 >>>>>>> are using R1 response type with timeout_ms changes to 30s. >>>>>>> >>>>>>> >>>>>>> >>>>>>> Earlier we used timeout_ms of 0 for CMD6 flush cache, and with=20 >>>>>>> it uses R1B response type and host will wait for busy state=20 >>>>>>> followed by response from device for CMD6 and then data lines go=20 >>>>>>> High. >>>>>>> >>>>>>> >>>>>>> >>>>>>> Now with timeout_ms changed to 30s, we use R1 response and SW=20 >>>>>>> waits for busy by checking for DAT0 line to go High. >>>>>> If I understand correctly, because of the timeout now set to 30s, >>>>>> MMC_RSP_BUSY becomes disabled in __mmc_switch() for your case in >>>>>> sdhci-tegra as well? >>>>> Yes >>>>>> >>>>>> In other words, mmc_poll_for_busy() is being called, which in your >>>>>> case means the ->card_busy() host ops (set to sdhci_card_busy() in >>>>>> your case) will be invoked to wait for the card to stop signal=20 >>>>>> busy on >>>>>> DAT0. >>>>>> >>>>>> This indicates to me, that the ->card_busy() ops returns zero to >>>>>> inform that the card is *not* busy, even if the card actually=20 >>>>>> signals >>>>>> busy? Is that correct? >>>>> Yes >>>>>> >>>>>>> >>>>>>> >>>>>>> With R1B type, host design after sending command at end of=20 >>>>>>> completion after end bit waits for 2 cycles for data line to go=20 >>>>>>> low (busy state from device) and waits for response cycles after=20 >>>>>>> which data lines will go back high and then we issue switch=20 >>>>>>> status CMD13. >>>>>>> >>>>>>> >>>>>>> >>>>>>> With R1 type, host after sending command and at end of=20 >>>>>>> completion after end bit, DATA lines will go high immediately as=20 >>>>>>> its R1 type and switch status CMD13 gets issued but by this time=20 >>>>>>> it looks like CMD6 on device side is still in flight for sending=20 >>>>>>> status and data. >>>>>> So, yes, using R1 instead of R1B triggers a different behaviour, but >>>>>> according to the eMMC spec it's perfectly allowed to issue a CMD13 >>>>>> even if the card signals busy on DAT0. The CMD13 is not using the=20 >>>>>> DATA >>>>>> lines, so this should work. >>>>>> >>>>>> If I understand correctly, your driver (and controller?) has issues >>>>>> with coping with this scenario. Is it something that can be fixed? >>>>>> >>>>>>> >>>>>>> 30s timeout is the wait time for data0 line to go high and=20 >>>>>>> mmc_busy_status will return success right away with R1 response=20 >>>>>>> type and SW sends switch status CMD13 but during that time on=20 >>>>>>> device side looks like still processing CMD6 as we are not=20 >>>>>>> waiting for enough time when we use R1 response type. >>>>>> Right, as stated above, isn't sdhci_card_busy() working for your=20 >>>>>> case? >>>>>> Can we fix it? >>>>> >>>>> sdhci_card_busy() returned 0 indicating its not busy. >>>>> >>>>> Based on our host design, When CMD6 is issued with R1 type, we=20 >>>>> program it as NO_RESPONSE and with this command complete interrupt=20 >>>>> happens right at end bit of command and there will be no transfer=20 >>>>> complete interrupt. >>>> *[Correction] Based on our host design, When CMD6 is issued with R1=20 >>>> type as we program it as NO_RESPONSE and with this command complete=20 >>>> interrupt happens right at end bit of command and there will be no=20 >>>> transfer complete interrupt. >>> >>> Sorry to correct wordings, I meant sdhci driver programs response=20 >>> type as NO_RESPONSE for CMD6. >>> >>> When CMD6 is issued with R1 type and as NO_RESPONSE, Based on our=20 >>> host design=C2=A0 command complete interrupt happens right at end bit o= f=20 >>> command and there will be no transfer complete interrupt. >>> >>> >> Sorry for confusion. Please ignore above on response. it is using=20 >> SHORT response for R1. So SW poll should be working. >> >> Will get back on checking on host design side internally. >> > Hi Ulf, > > Verified internally regarding the busy state over DATA0 Our host=20 > design has known minor bug where command complete interrupt is=20 > asserted after waiting for busy cycles from device.So because of this=20 > polling for card_busy() returns 0 (DAT0 line High) immediately as=20 > waiting for busy is taken care during command complete interrupt in=20 > host design. This behavior is same for R1 and R1B. > > >>>>> >>>>> When CMD6 is issued with R1B type, we program is as R1B RESP_SHORT=20 >>>>> and with this command complete is end bit of device resp and=20 >>>>> transfer complete interrupt will be when DAT0 LOW -> HIGH. >>>>> >>>>> Regardless of R1/R1B, device side CMD6 will always have busy state=20 >>>>> on D0 and response on CMD lines. >>>>> >>>>> There will be 2 clock cycles period after sending CMD6 for device=20 >>>>> to send busy state on data0. >>>>> >>>>> In case of R1 type, after sending command DAT will stay high and=20 >>>>> looks like we are polling for busy early before busy state has=20 >>>>> started and sending CMD13 while device is busy and sending=20 >>>>> response on CMD line is causing timeout. >>>>> >>>>> Probably with this specific case of CMD6 with R1 type, to wait for=20 >>>>> card busy we should poll for DAT0 to go Low first and then to go=20 >>>>> High?? >>>>> >>>>>> >> >>>>>>> >>>>>>> >>>>>>> >>>>>>> Actually we always use R1B with CMD6 as per spec. >>>>>> I fully agree that R1B is preferable, but it's not against the=20 >>>>>> spec to >>>>>> send CMD13 to poll for busy. >>>>>> >>>>>> Moreover, we need to cope with the scenario when the host has >>>>>> specified a maximum timeout that isn't sufficiently long enough for >>>>>> the requested operation. Do you have another proposal for how to >>>>>> manage this, but disabling MMC_RSP_BUSY? >>>>>> >>>>>> Let's assume you driver would get a R1B for the CMD6 (we force it), >>>>>> then what timeout would the driver be using if we would set >>>>>> cmd.busy_timeout to 30ms? >>>>>> > Sorry didn't understood clearly. Are you asking with 30s timeout, whats=20 the data timeout counter used? Because of above mentioned issue on our host where CMD interrupt happens=20 after busy state, poll for busy returns right away as not busy. So issuing CMD13 after CMD6-R1 followed by busy poll should be working.=20 But weird that with small delay of 1ms or debug print before CMD13 it=20 doesn't timeout and works all the time. >>>>>> Kind regards >>>>>> Uffe