linux-kernel - Re: [RFC PATCH v5 1/9] mmc: dw_mmc: Add external dma interface support

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Date:	Mon, 17 Aug 2015 14:27:47 +0800
From:	Shawn Lin <shawn.lin@...k-chips.com>
To:	Doug Anderson <dianders@...omium.org>,
	Heiko Stübner <heiko@...ech.de>
Cc:	shawn.lin@...k-chips.com, Jaehoon Chung <jh80.chung@...sung.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Vineet.Gupta1@...opsys.com, Wei Xu <xuwei5@...ilicon.com>,
	Joachim Eastwood <manabian@...il.com>,
	Alexey Brodkin <abrodkin@...opsys.com>,
	Kukjin Kim <kgene@...nel.org>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Russell King <linux@....linux.org.uk>,
	Zhangfei Gao <zhangfei.gao@...aro.org>,
	Jun Nie <jun.nie@...aro.org>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Govindraj Raja <govindraj.raja@...tec.com>,
	Arnd Bergmann <arnd@...db.de>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	linux-mips@...ux-mips.org,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC PATCH v5 1/9] mmc: dw_mmc: Add external dma interface
 support

在 2015/8/17 5:10, Doug Anderson 写道:
> Heiko,
>
> On Fri, Aug 14, 2015 at 3:13 PM, Heiko Stübner <heiko@...ech.de> wrote:
>> Hi Shawn,
>>
>> Am Freitag, 14. August 2015, 16:34:35 schrieb Shawn Lin:
>>> DesignWare MMC Controller can supports two types of DMA
>>> mode: external dma and internal dma. We get a RK312x platform
>>> integrated dw_mmc and ARM pl330 dma controller. This patch add
>>> edmac ops to support these platforms. I've tested it on RK312x
>>> platform with edmac mode and RK3288 platform with idmac mode.
>>>
>>> Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
>>
>> judging by your "from", I guess you're running this on some older Rockchip soc
>> without the idma? Because I tried testing this on a Radxa Rock, but only got
>> failures, from the start (failed to read card status register). In PIO mode
>> everything works again.
>>
>>
>> I guess I overlooked just some tiny detail, but to me the dma channel ids seem
>> correct after all. Maybe you have any hints what I'm doing wrong?
>
> If I were a guessing man (which I'm not), I'd guess that perhaps
> you're running into troubles with our friend the PL330.
>
> There appear to be strange issues with the PL330 on Rockchip SoCs.  I
> was only peripherally involved with them, but I know at least about
> some of the patches in our tree, like:
>

Thanks, Doug, that's the root cause. PL330 on Rockchip Socs need your 
patches, and we might need another patch to limit pl330 burst_len to 
16(Hmm...seems another quirks for rockchip but not on your tree);

Hi Heiko,
I just get a Radxa Rock luckily and test my patch based on 
http://radxa.com/Rock/Linux_Mainline. Yes, it can't work.

If you test my patchset on Rockchip platform, pls apply pl330 patch from 
my tree based on kernel 4.2-RC3. AND, temporary hack dw_mmc to limit 
pl330 burst_len to 16.
This is a dmaengine or pl330 problem(I guest it should be upstreamed 
later?), but my patchset is for *generic* dw_mmc to support emdac, so 
other platforms should never need the hack of pl330.

pl330.patch is for pl330 changes
r3xxx.patch is for pl330 quirks

AND pls limit burst_len to 16 for BROKRN pl330 of rockchips.
static int dw_mci_edmac_start_dma(
...
+        u32 burst_limit = 0;
+        u32 mburst;
+        u32 idx, rx_wmark, tx_wmark;

...
         /* Match burst msize with external dma config */
         fifoth_val = mci_readl(host, FIFOTH);
-	cfg.dst_maxburst = mszs[(fifoth_val >> 28) & 0x7];
-	cfg.src_maxburst = cfg.dst_maxburst;
+	/* HACK for BROKEN pl330 */
+       mburst = mszs[(fifoth_val >> 28) & 0x7];
+       burst_limit = 16;
+       if (mburst > burst_limit) {
+               mburst = burst_limit;
+               idx = (ilog2(mburst) > 0) ? (ilog2(mburst) - 1) : 0;
+               rx_wmark = mszs[idx] - 1;
+               tx_wmark = (host->fifo_depth) / 2;
+               fifoth_val = SDMMC_SET_FIFOTH(idx, rx_wmark, tx_wmark);
+               mci_writel(host, FIFOTH, fifoth_val);
+       }
+	cfg.dst_maxburst = mburst;
+       cfg.src_maxburst = cfg.dst_maxburst;


> https://chromium-review.googlesource.com/237607
> FROMLIST: DMA: pl330: support burst mode for dev-to-mem and mem-to-dev transmit
>
> https://chromium-review.googlesource.com/237393
> CHROMIUM: dmaengine: pl330: support quirks for some broken
>
> https://chromium-review.googlesource.com/237396
> CHROMIUM: dmaengine: pl330: add quirk for broken no flushp
>
> https://chromium-review.googlesource.com/237394
> CHROMIUM: ARM: dts: rockchip: Add broken-no-flushp into rk3288.dtsi
>
> https://chromium-review.googlesource.com/242063
> CHROMIUM: ASoC: rockchip_i2s: modify DMA max burst to 1
>
>
>


-- 
Shawn Lin

View attachment "pl330.patch" of type "text/plain" (7954 bytes)

View attachment "rk3xxxx.patch" of type "text/plain" (426 bytes)