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SubjectRe: [PATCH v2 06/16] ASoC: fsl_ssi: Clean up helper functions of trigger()
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On 11.01.2018 07:43, Nicolin Chen wrote:
> The trigger() calls fsl_ssi_tx_config() and fsl_ssi_rx_config(),
> and both of them jump to fsl_ssi_config(). And fsl_ssi_config()
> later calls another fsl_ssi_rxtx_config().
>
> However, the whole routine, especially fsl_ssi_config() function,
> is too complicated because of the folowing reasons:
> 1) It has to handle the concern of the opposite stream.
> 2) It has to handle cases of offline configurations support.
> 3) It has to handle enable and disable operations while they're
> mostly different.
>
> Since the enable and disable routines have more differences than
> TX and RX rountines, this patch simplifies these helper functions
> with the following changes:
> - Changing to two helper functions of enable and disable instead
> of TX and RX.
> - Removing fsl_ssi_rxtx_config() by separately integrating it to
> two newly introduced enable & disable functions.
>
> Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
> Tested-by: Caleb Crome <caleb@crome.org>
> ---
> sound/soc/fsl/fsl_ssi.c | 256 +++++++++++++++++++++++-------------------------
> 1 file changed, 122 insertions(+), 134 deletions(-)
>
> diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c
> index 263c067..09a571a 100644
> --- a/sound/soc/fsl/fsl_ssi.c
> +++ b/sound/soc/fsl/fsl_ssi.c
> @@ -378,31 +378,83 @@ static irqreturn_t fsl_ssi_isr(int irq, void *dev_id)
> }
>
> /**
> - * Enable or disable all rx/tx config flags at once
> + * Set SCR, SIER, STCR and SRCR registers with cached values in regvals
> + *
> + * Notes:
> + * 1) For offline_config SoCs, enable all necessary bits of both streams
> + * when 1st stream starts, even if the opposite stream will not start
> + * 2) It also clears FIFO before setting regvals; SOR is safe to set online
> */
> -static void fsl_ssi_rxtx_config(struct fsl_ssi *ssi, bool enable)
> +static void fsl_ssi_config_enable(struct fsl_ssi *ssi, bool tx)
> {
> - struct regmap *regs = ssi->regs;
> struct fsl_ssi_regvals *vals = ssi->regvals;
> + bool dir = tx ? TX : RX;

A similar case as in patch 3 of a bool variable used for a bit index.

> + u32 sier, srcr, stcr;
>
> - if (enable) {
> - regmap_update_bits(regs, REG_SSI_SIER,
> - vals[RX].sier | vals[TX].sier,
> - vals[RX].sier | vals[TX].sier);
> - regmap_update_bits(regs, REG_SSI_SRCR,
> - vals[RX].srcr | vals[TX].srcr,
> - vals[RX].srcr | vals[TX].srcr);
> - regmap_update_bits(regs, REG_SSI_STCR,
> - vals[RX].stcr | vals[TX].stcr,
> - vals[RX].stcr | vals[TX].stcr);
> + /* Clear dirty data in the FIFO; It also prevents channel slipping */
> + regmap_update_bits(ssi->regs, REG_SSI_SOR,
> + SSI_SOR_xX_CLR(tx), SSI_SOR_xX_CLR(tx));
> +
> + /*
> + * On offline_config SoCs, SxCR and SIER are already configured when
> + * the previous stream started. So skip all SxCR and SIER settings
> + * to prevent online reconfigurations, then jump to set SCR directly
> + */
> + if (ssi->soc->offline_config && ssi->streams)
> + goto enable_scr;
> +
> + if (ssi->soc->offline_config) {
> + /*
> + * Online reconfiguration not supported, so enable all bits for
> + * both streams at once to avoid necessity of reconfigurations
> + */
> + srcr = vals[RX].srcr | vals[TX].srcr;
> + stcr = vals[RX].stcr | vals[TX].stcr;
> + sier = vals[RX].sier | vals[TX].sier;
> } else {
> - regmap_update_bits(regs, REG_SSI_SRCR,
> - vals[RX].srcr | vals[TX].srcr, 0);
> - regmap_update_bits(regs, REG_SSI_STCR,
> - vals[RX].stcr | vals[TX].stcr, 0);
> - regmap_update_bits(regs, REG_SSI_SIER,
> - vals[RX].sier | vals[TX].sier, 0);
> + /* Otherwise, only set bits for the current stream */
> + srcr = vals[dir].srcr;
> + stcr = vals[dir].stcr;
> + sier = vals[dir].sier;
> }
> +
> + /* Configure SRCR, STCR and SIER at once */
> + regmap_update_bits(ssi->regs, REG_SSI_SRCR, srcr, srcr);
> + regmap_update_bits(ssi->regs, REG_SSI_STCR, stcr, stcr);
> + regmap_update_bits(ssi->regs, REG_SSI_SIER, sier, sier);
> +
> +enable_scr:
> + /*
> + * Start DMA before setting TE to avoid FIFO underrun
> + * which may cause a channel slip or a channel swap
> + *
> + * TODO: FIQ cases might also need this upon testing
> + */
> + if (ssi->use_dma && tx) {
> + int try = 100;
> + u32 sfcsr;
> +
> + /* Enable SSI first to send TX DMA request */
> + regmap_update_bits(ssi->regs, REG_SSI_SCR,
> + SSI_SCR_SSIEN, SSI_SCR_SSIEN);
> +
> + /* Busy wait until TX FIFO not empty -- DMA working */
> + do {
> + regmap_read(ssi->regs, REG_SSI_SFCSR, &sfcsr);
> + if (SSI_SFCSR_TFCNT0(sfcsr))
> + break;
> + } while (--try);
> +
> + /* FIFO still empty -- something might be wrong */
> + if (!SSI_SFCSR_TFCNT0(sfcsr))
> + dev_warn(ssi->dev, "Timeout waiting TX FIFO filling\n");
> + }
> + /* Enable all remaining bits in SCR */
> + regmap_update_bits(ssi->regs, REG_SSI_SCR,
> + vals[dir].scr, vals[dir].scr);
> +
> + /* Log the enabled stream to the mask */
> + ssi->streams |= BIT(dir);
> }
>
> /**
> @@ -426,66 +478,53 @@ static void fsl_ssi_rxtx_config(struct fsl_ssi *ssi, bool enable)
> ((vals) & _ssi_xor_shared_bits(vals, avals, aactive))
>
> /**
> - * Enable or disable SSI configuration.
> + * Unset SCR, SIER, STCR and SRCR registers with cached values in regvals
> + *
> + * Notes:
> + * 1) For offline_config SoCs, to avoid online reconfigurations, disable all
> + * bits of both streams at once when the last stream is abort to end
> + * 2) It also clears FIFO after unsetting regvals; SOR is safe to set online
> */
> -static void fsl_ssi_config(struct fsl_ssi *ssi, bool enable,
> - struct fsl_ssi_regvals *vals)
> +static void fsl_ssi_config_disable(struct fsl_ssi *ssi, bool tx)
> {
> - bool tx = &ssi->regvals[TX] == vals;
> + struct fsl_ssi_regvals *vals, *avals;
> + u32 sier, srcr, stcr, scr;
> bool dir = tx ? TX : RX;
> - struct regmap *regs = ssi->regs;
> - struct fsl_ssi_regvals *avals;
> bool aactive;
>
> /* Check if the opposite stream is active */
> aactive = ssi->streams & BIT(!dir);
>
> - /* Get the opposite direction to keep its values untouched */
> - if (&ssi->regvals[RX] == vals)
> - avals = &ssi->regvals[TX];
> - else
> - avals = &ssi->regvals[RX];
> + vals = &ssi->regvals[dir];>
> - if (!enable) {
> - /*
> - * To keep the other stream safe, exclude shared bits between
> - * both streams, and get safe bits to disable current stream
> - */
> - u32 scr = ssi_excl_shared_bits(vals->scr, avals->scr, aactive);
> - /* Safely disable SCR register for the stream */
> - regmap_update_bits(regs, REG_SSI_SCR, scr, 0);
> -
> - /* Log the disabled stream to the mask */
> - ssi->streams &= ~BIT(dir);
> - }
> + /* Get regvals of the opposite stream to keep opposite stream safe */
> + avals = &ssi->regvals[!dir];
^
The same implicit assumption here as in patch 4.

Maciej

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