[PATCH] i2c: at91: introduce probe deferring
Ludovic Desroches
ludovic.desroches at atmel.com
Wed Nov 19 02:14:03 PST 2014
On Wed, Nov 19, 2014 at 10:47:15AM +0100, Arnd Bergmann wrote:
> On Wednesday 19 November 2014 10:16:47 Wolfram Sang wrote:
> > On Fri, Nov 14, 2014 at 02:47:59PM +0100, Ludovic Desroches wrote:
> > > Return probe defer if requesting a dma channel without a dma controller probed.
> > >
> > > Signed-off-by: Ludovic Desroches <ludovic.desroches at atmel.com>
> > > ---
> > > drivers/i2c/busses/i2c-at91.c | 22 ++++++++++++++++------
> > > 1 file changed, 16 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
> > > index 77fb647..df3f4c4 100644
> > > --- a/drivers/i2c/busses/i2c-at91.c
> > > +++ b/drivers/i2c/busses/i2c-at91.c
> > > @@ -679,14 +679,21 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
> > > dma_cap_zero(mask);
> > > dma_cap_set(DMA_SLAVE, mask);
> > >
> > > - dma->chan_tx = dma_request_slave_channel_compat(mask, filter, pdata,
> > > - dev->dev, "tx");
> > > - if (!dma->chan_tx) {
> > > + dma->chan_tx = dma_request_slave_channel_reason(dev->dev, "tx");
> >
> > Will it cause regressions if you drop the compat-version of requesting
> > a channel?
>
> I got curious about this, since the patch looks obviously wrong, but
> actually it's ok. However the entire DMA support for non-DT platforms
> can be dropped in this driver, see patch below
>
> > > + if (IS_ERR(dma->chan_tx)) {
> > > + ret = PTR_ERR(dma->chan_tx);
> > > + if (ret == -EPROBE_DEFER) {
> > > + dev_warn(dev->dev, "no DMA channel available at the moment\n");
> >
> > I'd say drop this warning. The core usually prints when deferred probing
> > takes place.
>
> Definitely yes.
>
> Arnd
> 8<---
> [PATCH] i2c: at91: remove legacy DMA supoprt
>
> Since at91sam9g45 is now DT-only, all DMA capable users of this driver are
> using the DT case, and the legacy support can be removed. While at it, fix
> the deferred probe case.
>
> Signed-off-by: Arnd Bergmann <arnd at arndb.de>
Acked-by: Ludovic Desroches <ludovic.desroches at atmel.com>
Thanks
>
> diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
> index 917d54588d95..534f4c07bfb6 100644
> --- a/drivers/i2c/busses/i2c-at91.c
> +++ b/drivers/i2c/busses/i2c-at91.c
> @@ -72,8 +72,6 @@ struct at91_twi_pdata {
> unsigned clk_max_div;
> unsigned clk_offset;
> bool has_unre_flag;
> - bool has_dma_support;
> - struct at_dma_slave dma_slave;
> };
>
> struct at91_twi_dma {
> @@ -541,35 +539,30 @@ static struct at91_twi_pdata at91rm9200_config = {
> .clk_max_div = 5,
> .clk_offset = 3,
> .has_unre_flag = true,
> - .has_dma_support = false,
> };
>
> static struct at91_twi_pdata at91sam9261_config = {
> .clk_max_div = 5,
> .clk_offset = 4,
> .has_unre_flag = false,
> - .has_dma_support = false,
> };
>
> static struct at91_twi_pdata at91sam9260_config = {
> .clk_max_div = 7,
> .clk_offset = 4,
> .has_unre_flag = false,
> - .has_dma_support = false,
> };
>
> static struct at91_twi_pdata at91sam9g20_config = {
> .clk_max_div = 7,
> .clk_offset = 4,
> .has_unre_flag = false,
> - .has_dma_support = false,
> };
>
> static struct at91_twi_pdata at91sam9g10_config = {
> .clk_max_div = 7,
> .clk_offset = 4,
> .has_unre_flag = false,
> - .has_dma_support = false,
> };
>
> static const struct platform_device_id at91_twi_devtypes[] = {
> @@ -598,7 +591,6 @@ static struct at91_twi_pdata at91sam9x5_config = {
> .clk_max_div = 7,
> .clk_offset = 4,
> .has_unre_flag = false,
> - .has_dma_support = true,
> };
>
> static const struct of_device_id atmel_twi_dt_ids[] = {
> @@ -627,30 +619,11 @@ static const struct of_device_id atmel_twi_dt_ids[] = {
> MODULE_DEVICE_TABLE(of, atmel_twi_dt_ids);
> #endif
>
> -static bool filter(struct dma_chan *chan, void *pdata)
> -{
> - struct at91_twi_pdata *sl_pdata = pdata;
> - struct at_dma_slave *sl;
> -
> - if (!sl_pdata)
> - return false;
> -
> - sl = &sl_pdata->dma_slave;
> - if (sl && (sl->dma_dev == chan->device->dev)) {
> - chan->private = sl;
> - return true;
> - } else {
> - return false;
> - }
> -}
> -
> static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
> {
> int ret = 0;
> - struct at91_twi_pdata *pdata = dev->pdata;
> struct dma_slave_config slave_config;
> struct at91_twi_dma *dma = &dev->dma;
> - dma_cap_mask_t mask;
>
> memset(&slave_config, 0, sizeof(slave_config));
> slave_config.src_addr = (dma_addr_t)phy_addr + AT91_TWI_RHR;
> @@ -661,22 +634,17 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
> slave_config.dst_maxburst = 1;
> slave_config.device_fc = false;
>
> - dma_cap_zero(mask);
> - dma_cap_set(DMA_SLAVE, mask);
> -
> - dma->chan_tx = dma_request_slave_channel_compat(mask, filter, pdata,
> - dev->dev, "tx");
> - if (!dma->chan_tx) {
> - dev_err(dev->dev, "can't get a DMA channel for tx\n");
> - ret = -EBUSY;
> + dma->chan_tx = dma_request_slave_channel_reason(dev->dev, "tx");
> + if (IS_ERR(dma->chan_tx)) {
> + ret = PTR_ERR(dma->chan_tx);
> + dma->chan_tx = NULL;
> goto error;
> }
>
> - dma->chan_rx = dma_request_slave_channel_compat(mask, filter, pdata,
> - dev->dev, "rx");
> - if (!dma->chan_rx) {
> - dev_err(dev->dev, "can't get a DMA channel for rx\n");
> - ret = -EBUSY;
> + dma->chan_rx = dma_request_slave_channel_reason(dev->dev, "rx");
> + if (IS_ERR(dma->chan_rx)) {
> + ret = PTR_ERR(dma->chan_rx);
> + dma->chan_rx = NULL;
> goto error;
> }
>
> @@ -697,6 +665,7 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
> sg_init_table(&dma->sg, 1);
> dma->buf_mapped = false;
> dma->xfer_in_progress = false;
> + dev->use_dma = true;
>
> dev_info(dev->dev, "using %s (tx) and %s (rx) for DMA transfers\n",
> dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
> @@ -704,7 +673,8 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
> return ret;
>
> error:
> - dev_info(dev->dev, "can't use DMA\n");
> + if (ret != -EPROBE_DEFER)
> + dev_info(dev->dev, "can't use DMA, error %d\n", ret);
> if (dma->chan_rx)
> dma_release_channel(dma->chan_rx);
> if (dma->chan_tx)
> @@ -772,10 +742,8 @@ static int at91_twi_probe(struct platform_device *pdev)
> }
> clk_prepare_enable(dev->clk);
>
> - if (dev->pdata->has_dma_support) {
> - if (at91_twi_configure_dma(dev, phy_addr) == 0)
> - dev->use_dma = true;
> - }
> + if (dev->of_node)
> + at91_twi_configure_dma(dev, phy_addr);
>
> rc = of_property_read_u32(dev->dev->of_node, "clock-frequency",
> &bus_clk_rate);
>
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