dma: mxs-dma: Fix channel reset hardware bug (702e94d6) · Commits · 戴 / test

drivers/dma/mxs-dma.c

+27 −2

Original line number	Diff line number	Diff line
		@@ -60,6 +60,7 @@
		(((dma_is_apbh(d) && apbh_is_old(d)) ? 0x080 : 0x140) + (n) * 0x70)
		#define HW_APBHX_CHn_BAR(d, n) \
		(((dma_is_apbh(d) && apbh_is_old(d)) ? 0x070 : 0x130) + (n) * 0x70)
		#define HW_APBX_CHn_DEBUG1(d, n) (0x150 + (n) * 0x70)

		/*
		* ccw bits definitions
		@@ -204,13 +205,37 @@ static void mxs_dma_reset_chan(struct mxs_dma_chan *mxs_chan)
		struct mxs_dma_engine *mxs_dma = mxs_chan->mxs_dma;
		int chan_id = mxs_chan->chan.chan_id;

		if (dma_is_apbh(mxs_dma) && apbh_is_old(mxs_dma))
		if (dma_is_apbh(mxs_dma) && apbh_is_old(mxs_dma)) {
		writel(1 << (chan_id + BP_APBH_CTRL0_RESET_CHANNEL),
		mxs_dma->base + HW_APBHX_CTRL0 + STMP_OFFSET_REG_SET);
		else
		} else {
		unsigned long elapsed = 0;
		const unsigned long max_wait = 50000; /* 50ms */
		void __iomem *reg_dbg1 = mxs_dma->base +
		HW_APBX_CHn_DEBUG1(mxs_dma, chan_id);

		/*
		* On i.MX28 APBX, the DMA channel can stop working if we reset
		* the channel while it is in READ_FLUSH (0x08) state.
		* We wait here until we leave the state. Then we trigger the
		* reset. Waiting a maximum of 50ms, the kernel shouldn't crash
		* because of this.
		*/
		while ((readl(reg_dbg1) & 0xf) == 0x8 && elapsed < max_wait) {
		udelay(100);
		elapsed += 100;
		}

		if (elapsed >= max_wait)
		dev_err(&mxs_chan->mxs_dma->pdev->dev,
		"Failed waiting for the DMA channel %d to leave state READ_FLUSH, trying to reset channel in READ_FLUSH state now\n",
		chan_id);


		writel(1 << (chan_id + BP_APBHX_CHANNEL_CTRL_RESET_CHANNEL),
		mxs_dma->base + HW_APBHX_CHANNEL_CTRL + STMP_OFFSET_REG_SET);
		}
		}

		static void mxs_dma_enable_chan(struct mxs_dma_chan *mxs_chan)
		{

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