Re: [PATCH v2 2/2] dma-contiguous: Use fallback alloc_pages for single pages

From: Masahiro Yamada
Date: Fri Aug 23 2019 - 08:50:37 EST

On Tue, May 7, 2019 at 7:36 AM Nicolin Chen <nicoleotsuka@xxxxxxxxx> wrote:
>
> The addresses within a single page are always contiguous, so it's
> not so necessary to always allocate one single page from CMA area.
> Since the CMA area has a limited predefined size of space, it may
> run out of space in heavy use cases, where there might be quite a
> lot CMA pages being allocated for single pages.
>
> However, there is also a concern that a device might care where a
> page comes from -- it might expect the page from CMA area and act
> differently if the page doesn't.
>
> This patch tries to use the fallback alloc_pages path, instead of
> one-page size allocations from the global CMA area in case that a
> device does not have its own CMA area. This'd save resources from
> the CMA global area for more CMA allocations, and also reduce CMA
> fragmentations resulted from trivial allocations.
>
> Signed-off-by: Nicolin Chen <nicoleotsuka@xxxxxxxxx>


This commit (bd2e75633c8012fc8a7431c82fda66237133bf7e)
broke the DMA for my MMC driver in the following way:




[ 1.876755] mmc0: ADMA error
[ 1.883385] mmc0: sdhci: ============ SDHCI REGISTER DUMP ===========
[ 1.889834] mmc0: sdhci: Sys addr: 0x00000000 | Version: 0x00000002
[ 1.896284] mmc0: sdhci: Blk size: 0x00007200 | Blk cnt: 0x00000001
[ 1.902733] mmc0: sdhci: Argument: 0x00000000 | Trn mode: 0x00000013
[ 1.909182] mmc0: sdhci: Present: 0x01ff02f6 | Host ctl: 0x00000019
[ 1.915631] mmc0: sdhci: Power: 0x0000000b | Blk gap: 0x00000000
[ 1.922081] mmc0: sdhci: Wake-up: 0x00000000 | Clock: 0x0000fa07
[ 1.928530] mmc0: sdhci: Timeout: 0x0000000b | Int stat: 0x00000001
[ 1.934981] mmc0: sdhci: Int enab: 0x03ff008b | Sig enab: 0x03ff008b
[ 1.941429] mmc0: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000001
[ 1.947880] mmc0: sdhci: Caps: 0x546ec800 | Caps_1: 0x00000000
[ 1.954329] mmc0: sdhci: Cmd: 0x0000083a | Max curr: 0x00000000
[ 1.960778] mmc0: sdhci: Resp[0]: 0x00000900 | Resp[1]: 0xffffffff
[ 1.967229] mmc0: sdhci: Resp[2]: 0x320f5903 | Resp[3]: 0x3fd05e00
[ 1.973678] mmc0: sdhci: Host ctl2: 0x00000000
[ 1.978125] mmc0: sdhci: ADMA Err: 0x00000001 | ADMA Ptr: 0x000000013965b200
[ 1.985271] mmc0: sdhci: ============================================
[ 1.991758] mmc0: error -5 whilst initialising MMC card
[ 1.991913] 43fb0000.uart: ttyS1 at MMIO 0x43fb0000 (irq = 0,
base_baud = 768000) is a 16550A
[ 2.011011] hctosys: unable to open rtc device (rtc0)
[ 2.017694] Freeing unused kernel memory: 2368K
[ 2.027131] Run /init as init process
Starting syslogd: OK
Starting klogd: OK
Initializing random number generator... [ 2.074399] random: dd:
uninitialized urandom read (512 bytes read)
done.
Starting network: OK
[ 2.109593] mmc0: ADMA error
[ 2.112488] mmc0: sdhci: ============ SDHCI REGISTER DUMP ===========
[ 2.118941] mmc0: sdhci: Sys addr: 0x00000000 | Version: 0x00000002
[ 2.125389] mmc0: sdhci: Blk size: 0x00007200 | Blk cnt: 0x00000001
[ 2.131840] mmc0: sdhci: Argument: 0x00000000 | Trn mode: 0x00000013
[ 2.138289] mmc0: sdhci: Present: 0x01ff02f6 | Host ctl: 0x00000019
[ 2.144738] mmc0: sdhci: Power: 0x0000000b | Blk gap: 0x00000000
[ 2.151188] mmc0: sdhci: Wake-up: 0x00000000 | Clock: 0x00004e47
[ 2.157637] mmc0: sdhci: Timeout: 0x0000000b | Int stat: 0x00000001
[ 2.164087] mmc0: sdhci: Int enab: 0x03ff008b | Sig enab: 0x03ff008b
[ 2.170536] mmc0: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000001
[ 2.176987] mmc0: sdhci: Caps: 0x546ec800 | Caps_1: 0x00000000
[ 2.183435] mmc0: sdhci: Cmd: 0x0000083a | Max curr: 0x00000000
[ 2.189886] mmc0: sdhci: Resp[0]: 0x00000900 | Resp[1]: 0xffffffff
[ 2.196335] mmc0: sdhci: Resp[2]: 0x320f5903 | Resp[3]: 0x3fd05e00
[ 2.202784] mmc0: sdhci: Host ctl2: 0x00000000
[ 2.207232] mmc0: sdhci: ADMA Err: 0x00000001 | ADMA Ptr: 0x000000013965b200
[ 2.214379] mmc0: sdhci: ============================================

[ 2.220881] mmc0: error -5 whilst initialising MMC card
Welcome to Buildroot
buildroot login: [ 2.332786] mmc0: ADMA error
[ 2.335668] mmc0: sdhci: ============ SDHCI REGISTER DUMP ===========
[ 2.342119] mmc0: sdhci: Sys addr: 0x00000000 | Version: 0x00000002
[ 2.348568] mmc0: sdhci: Blk size: 0x00007200 | Blk cnt: 0x00000001
[ 2.355018] mmc0: sdhci: Argument: 0x00000000 | Trn mode: 0x00000013
[ 2.361468] mmc0: sdhci: Present: 0x01ff02f6 | Host ctl: 0x00000019
[ 2.367917] mmc0: sdhci: Power: 0x0000000b | Blk gap: 0x00000000
[ 2.374367] mmc0: sdhci: Wake-up: 0x00000000 | Clock: 0x0000f447
[ 2.380816] mmc0: sdhci: Timeout: 0x0000000b | Int stat: 0x00000001
[ 2.387267] mmc0: sdhci: Int enab: 0x03ff008b | Sig enab: 0x03ff008b
[ 2.393716] mmc0: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000001
[ 2.400166] mmc0: sdhci: Caps: 0x546ec800 | Caps_1: 0x00000000
[ 2.406615] mmc0: sdhci: Cmd: 0x0000083a | Max curr: 0x00000000
[ 2.413065] mmc0: sdhci: Resp[0]: 0x00000900 | Resp[1]: 0xffffffff
[ 2.419515] mmc0: sdhci: Resp[2]: 0x320f5903 | Resp[3]: 0x3fd05e00
[ 2.425963] mmc0: sdhci: Host ctl2: 0x00000000
[ 2.430412] mmc0: sdhci: ADMA Err: 0x00000001 | ADMA Ptr: 0x000000013965b200
[ 2.437557] mmc0: sdhci: ============================================
[ 2.444031] mmc0: error -5 whilst initialising MMC card
[ 2.572203] mmc0: ADMA error
[ 2.575089] mmc0: sdhci: ============ SDHCI REGISTER DUMP ===========
[ 2.581540] mmc0: sdhci: Sys addr: 0x00000000 | Version: 0x00000002
[ 2.587989] mmc0: sdhci: Blk size: 0x00007200 | Blk cnt: 0x00000001
[ 2.594439] mmc0: sdhci: Argument: 0x00000000 | Trn mode: 0x00000013
[ 2.600889] mmc0: sdhci: Present: 0x01ef02f6 | Host ctl: 0x00000019
[ 2.607339] mmc0: sdhci: Power: 0x0000000b | Blk gap: 0x00000000
[ 2.613788] mmc0: sdhci: Wake-up: 0x00000000 | Clock: 0x0000e8c7
[ 2.620237] mmc0: sdhci: Timeout: 0x0000000b | Int stat: 0x00000001
[ 2.626686] mmc0: sdhci: Int enab: 0x03ff008b | Sig enab: 0x03ff008b
[ 2.633137] mmc0: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000001
[ 2.639586] mmc0: sdhci: Caps: 0x546ec800 | Caps_1: 0x00000000
[ 2.646036] mmc0: sdhci: Cmd: 0x0000083a | Max curr: 0x00000000
[ 2.652485] mmc0: sdhci: Resp[0]: 0x00000900 | Resp[1]: 0xffffffff
[ 2.658936] mmc0: sdhci: Resp[2]: 0x320f5903 | Resp[3]: 0x3fd05e00
[ 2.665384] mmc0: sdhci: Host ctl2: 0x00000000
[ 2.669832] mmc0: sdhci: ADMA Err: 0x00000001 | ADMA Ptr: 0x000000013965b200
[ 2.676979] mmc0: sdhci: ============================================
[ 2.683450] mmc0: error -5 whilst initialising MMC card

CTRL-A Z for help | 115200 8N1 | NOR | Minicom 2.7.1 | VT102 | Offline
| ttyUSB0

Reverting this commit fixed the problem.



--
Best Regards
Masahiro Yamada