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SubjectRe: [PATCH 21/32] mmc: bcm2835-sdhost: Add new driver for the internal SD controller.
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On Wednesday, June 1, 2016 11:43:30 PM CEST Gerd Hoffmann wrote:

> +static void bcm2835_sdhost_reset_internal(struct bcm2835_host *host)
> +{
> + u32 temp;
> +
> + bcm2835_sdhost_set_power(host, false);
> +
> + bcm2835_sdhost_write(host, 0, SDCMD);
> + bcm2835_sdhost_write(host, 0, SDARG);
> + bcm2835_sdhost_write(host, 0xf00000, SDTOUT);
> + bcm2835_sdhost_write(host, 0, SDCDIV);
> + bcm2835_sdhost_write(host, 0x7f8, SDHSTS); /* Write 1s to clear */
> + bcm2835_sdhost_write(host, 0, SDHCFG);
> + bcm2835_sdhost_write(host, 0, SDHBCT);
> + bcm2835_sdhost_write(host, 0, SDHBLC);
> +
> + /* Limit fifo usage due to silicon bug */
> + temp = bcm2835_sdhost_read(host, SDEDM);
> + temp &= ~((SDEDM_THRESHOLD_MASK << SDEDM_READ_THRESHOLD_SHIFT) |
> + (SDEDM_THRESHOLD_MASK << SDEDM_WRITE_THRESHOLD_SHIFT));
> + temp |= (FIFO_READ_THRESHOLD << SDEDM_READ_THRESHOLD_SHIFT) |
> + (FIFO_WRITE_THRESHOLD << SDEDM_WRITE_THRESHOLD_SHIFT);
> + bcm2835_sdhost_write(host, temp, SDEDM);
> + mdelay(10);
> + bcm2835_sdhost_set_power(host, true);
> + mdelay(10);

Are you sure you cannot use msleep() here?

> + host->clock = 0;
> + bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
> + bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
> + mmiowb();
> +}

What is the barrier for? Same question for all the other instances

> +
> +static void bcm2835_sdhost_reset(struct mmc_host *mmc)
> +{
> + struct bcm2835_host *host = mmc_priv(mmc);
> + unsigned long flags;
> +
> + spin_lock_irqsave(&host->lock, flags);
> + bcm2835_sdhost_reset_internal(host);
> + spin_unlock_irqrestore(&host->lock, flags);
> +}

The spinlock seems to only protect the reset from happening concurrently
with bcm2835_sdhost_dma_complete() here. So if you ensure that this
function is no longer pending, you can probably use msleep() above.

> +static void bcm2835_sdhost_set_ios(struct mmc_host *mmc, struct mmc_ios *ios);

Maybe rearrange the order of the functions to avoid forward declarations?

> + spin_lock_init(&host->lock);
> +
> + if (IS_ERR_OR_NULL(host->dma_chan_tx) ||
> + IS_ERR_OR_NULL(host->dma_chan_rx)) {
> + pr_err("%s: unable to initialise DMA channels. Falling back to PIO\n",
> + mmc_hostname(mmc));

When are these ever NULL?

> + /* Parse OF address directly to get the physical address for
> + * DMA to our registers.
> + */
> + host->phys_addr = be32_to_cpup(of_get_address(pdev->dev.of_node, 0,
> + NULL, NULL));

This looks broken on 64-bit systems when #address-cells=<2>, or if there
is an intermediate bus with a non-empty ranges property.

What's wrong with platform_get_resource(pdev, IORESOURCE_MEM, 0)?

Arnd

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