Re: [PATCH v3] mmc: moxart: fix probe logic

Ulf Hansson
2015-02-03T08:02:23Z

On 2 February 2015 at 16:43, Jonas Jensen <jonas.jensen@gmail.com> wrote:
> Jonas Jensen wanted to submit a patch for these, but apparently
> forgot about it. I stumbled over this symptom first:
>
> drivers/built-in.o: In function `moxart_probe':
> :(.text+0x2af128): undefined reference to `of_dma_request_slave_channel'
>
> This is because of_dma_request_slave_channel is an internal helper
> and not exported to loadable module. I'm changing the driver to
> use dma_request_slave_channel_reason() instead.
>
> Further problems from inspection:
>
> * The remove function must not call kfree on the host pointer,
> because it is allocated together with the mmc_host.
>
> * The clock is never released
>
> * The dma_cap_mask_t is completely unused and can be removed
>
> * deferred probing does not work if the dma driver is loaded
> after the mmc driver.
>
> This patch should fix all of the above.
>
> Signed-off-by: Jonas Jensen <jonas.jensen@gmail.com>
> ---
>
> Notes:
> This is a forward (with a single line fix) of Arnd's v2 patch.
>
> v2: do not call clk_put() on an error pointer
> v3: fix NULL dereference on host->clk
>
> Applies to next-20150113
>
> drivers/mmc/host/moxart-mmc.c | 34 +++++++++++++++++++---------------
> 1 file changed, 19 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
> index d2a1ef6..6ab57d1e 100644
> --- a/drivers/mmc/host/moxart-mmc.c
> +++ b/drivers/mmc/host/moxart-mmc.c
> @@ -17,6 +17,7 @@
> #include <linux/init.h>
> #include <linux/platform_device.h>
> #include <linux/delay.h>
> +#include <linux/errno.h>
> #include <linux/interrupt.h>
> #include <linux/blkdev.h>
> #include <linux/dma-mapping.h>
> @@ -131,6 +132,7 @@ struct moxart_host {
> struct mmc_host *mmc;
> struct mmc_request *mrq;
> struct scatterlist *cur_sg;
> + struct clk *clk;
> struct completion dma_complete;
> struct completion pio_complete;
>
> @@ -560,9 +562,7 @@ static int moxart_probe(struct platform_device *pdev)
> struct mmc_host *mmc;
> struct moxart_host *host = NULL;
> struct dma_slave_config cfg;
> - struct clk *clk;
> void __iomem *reg_mmc;
> - dma_cap_mask_t mask;
> int irq, ret;
> u32 i;
>
> @@ -573,6 +573,8 @@ static int moxart_probe(struct platform_device *pdev)
> goto out;
> }
>
> + host = mmc_priv(mmc);
> +
> ret = of_address_to_resource(node, 0, &res_mmc);
> if (ret) {
> dev_err(dev, "of_address_to_resource failed\n");
> @@ -586,10 +588,11 @@ static int moxart_probe(struct platform_device *pdev)
> goto out;
> }
>
> - clk = of_clk_get(node, 0);

This code would be simpler using devm_clk_get(), since then error
wouldn't be needed.

Any reason to why you don't want to use that?

> - if (IS_ERR(clk)) {
> + host->clk = of_clk_get(node, 0);
> + if (IS_ERR(host->clk)) {
> dev_err(dev, "of_clk_get failed\n");
> - ret = PTR_ERR(clk);
> + ret = PTR_ERR(host->clk);
> + host->clk = NULL;
> goto out;
> }
>
> @@ -603,18 +606,14 @@ static int moxart_probe(struct platform_device *pdev)
> if (ret)
> goto out;
>
> - dma_cap_zero(mask);
> - dma_cap_set(DMA_SLAVE, mask);
> -
> - host = mmc_priv(mmc);
> host->mmc = mmc;
> host->base = reg_mmc;
> host->reg_phys = res_mmc.start;
> host->timeout = msecs_to_jiffies(1000);
> - host->sysclk = clk_get_rate(clk);
> + host->sysclk = clk_get_rate(host->clk);
> host->fifo_width = readl(host->base + REG_FEATURE) << 2;
> - host->dma_chan_tx = of_dma_request_slave_channel(node, "tx");
> - host->dma_chan_rx = of_dma_request_slave_channel(node, "rx");
> + host->dma_chan_tx = dma_request_slave_channel_reason(dev, "tx");
> + host->dma_chan_rx = dma_request_slave_channel_reason(dev, "rx");
>
> spin_lock_init(&host->lock);
>
> @@ -624,6 +623,11 @@ static int moxart_probe(struct platform_device *pdev)
> mmc->ocr_avail = 0xffff00; /* Support 2.0v - 3.6v power. */
>
> if (IS_ERR(host->dma_chan_tx) || IS_ERR(host->dma_chan_rx)) {
> + if (PTR_ERR(host->dma_chan_tx) == -EPROBE_DEFER ||
> + PTR_ERR(host->dma_chan_rx) == -EPROBE_DEFER) {
> + ret = -EPROBE_DEFER;
> + goto out;
> + }
> dev_dbg(dev, "PIO mode transfer enabled\n");
> host->have_dma = false;
> } else {
> @@ -677,6 +681,8 @@ static int moxart_probe(struct platform_device *pdev)
> return 0;
>
> out:
> + if (host->clk)
> + clk_put(host->clk);
> if (mmc)
> mmc_free_host(mmc);
> return ret;
> @@ -694,6 +700,7 @@ static int moxart_remove(struct platform_device *pdev)
> dma_release_channel(host->dma_chan_tx);
> if (!IS_ERR(host->dma_chan_rx))
> dma_release_channel(host->dma_chan_rx);
> + clk_put(host->clk);
> mmc_remove_host(mmc);
> mmc_free_host(mmc);
>
> @@ -702,9 +709,6 @@ static int moxart_remove(struct platform_device *pdev)
> writel(readl(host->base + REG_CLOCK_CONTROL) | CLK_OFF,
> host->base + REG_CLOCK_CONTROL);
> }
> -
> - kfree(host);
> -
> return 0;
> }
>
> --
> 1.8.2.1
>

Kind regards
Uffe