RE: [PATCH 1/4] dmaengine: imx-sdma: Support allocate memory from internal SRAM (iram)

[Joy Zou]

> -----Original Message-----
> From: Frank Li <frank.li@xxxxxxx>
> Sent: 2024年3月6日 23:23
> To: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> Cc: Vinod Koul <vkoul@xxxxxxxxxx>; Shawn Guo <shawnguo@xxxxxxxxxx>;
> Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>; Pengutronix Kernel Team
> <kernel@xxxxxxxxxxxxxx>; Fabio Estevam <festevam@xxxxxxxxx>;
> dl-linux-imx <linux-imx@xxxxxxx>; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> dmaengine@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> imx@xxxxxxxxxxxxxxx; Nicolin Chen <b42378@xxxxxxxxxxxxx>; S.J. Wang
> <shengjiu.wang@xxxxxxx>; Joy Zou <joy.zou@xxxxxxx>
> Subject: Re: [PATCH 1/4] dmaengine: imx-sdma: Support allocate memory
> from internal SRAM (iram)
> 
> On Wed, Mar 06, 2024 at 10:55:00AM +0100, Alexander Stein wrote:
> > Hi Frank,
> >
> > thanks for the patch.
> >
> > Am Montag, 4. März 2024, 05:32:53 CET schrieb Frank Li:
> > > From: Nicolin Chen <b42378@xxxxxxxxxxxxx>
> > >
> > > Allocate memory from SoC internal SRAM to reduce DDR access and keep
> > > DDR in lower power state (such as self-referesh) longer.
> > >
> > > Check iram_pool before sdma_init() so that ccb/context could be
> > > allocated from iram because DDR maybe in self-referesh in lower
> > > power audio case while sdma still running.
> > >
> > > Reviewed-by: Shengjiu Wang <shengjiu.wang@xxxxxxx>
> > > Signed-off-by: Nicolin Chen <b42378@xxxxxxxxxxxxx>
> > > Signed-off-by: Joy Zou <joy.zou@xxxxxxx>
> > > Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> > > ---
> > >  drivers/dma/imx-sdma.c | 53
> > > +++++++++++++++++++++++++++++++++++++-------------
> > >  1 file changed, 40 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c index
> > > 9b42f5e96b1e0..9a6d8f1e9ff63 100644
> > > --- a/drivers/dma/imx-sdma.c
> > > +++ b/drivers/dma/imx-sdma.c
> > > @@ -24,6 +24,7 @@
> > >  #include <linux/semaphore.h>
> > >  #include <linux/spinlock.h>
> > >  #include <linux/device.h>
> > > +#include <linux/genalloc.h>
> > >  #include <linux/dma-mapping.h>
> > >  #include <linux/firmware.h>
> > >  #include <linux/slab.h>
> > > @@ -516,6 +517,7 @@ struct sdma_engine {
> > >  	void __iomem			*regs;
> > >  	struct sdma_context_data	*context;
> > >  	dma_addr_t			context_phys;
> > > +	dma_addr_t			ccb_phys;
> > >  	struct dma_device		dma_device;
> > >  	struct clk			*clk_ipg;
> > >  	struct clk			*clk_ahb;
> > > @@ -531,6 +533,7 @@ struct sdma_engine {
> > >  	/* clock ratio for AHB:SDMA core. 1:1 is 1, 2:1 is 0*/
> > >  	bool				clk_ratio;
> > >  	bool                            fw_loaded;
> > > +	struct gen_pool			*iram_pool;
> > >  };
> > >
> > >  static int sdma_config_write(struct dma_chan *chan, @@ -1358,8
> > > +1361,14 @@ static int sdma_request_channel0(struct sdma_engine
> > > *sdma)  {
> > >  	int ret = -EBUSY;
> > >
> > > -	sdma->bd0 = dma_alloc_coherent(sdma->dev, PAGE_SIZE,
> &sdma->bd0_phys,
> > > -				       GFP_NOWAIT);
> > > +	if (sdma->iram_pool)
> > > +		sdma->bd0 = gen_pool_dma_alloc(sdma->iram_pool,
> > > +					sizeof(struct sdma_buffer_descriptor),
> > > +					&sdma->bd0_phys);
> > > +	else
> > > +		sdma->bd0 = dma_alloc_coherent(sdma->dev,
> > > +					sizeof(struct sdma_buffer_descriptor),
> > > +					&sdma->bd0_phys, GFP_NOWAIT);
> > >  	if (!sdma->bd0) {
> > >  		ret = -ENOMEM;
> > >  		goto out;
> > > @@ -1379,10 +1388,14 @@ static int sdma_request_channel0(struct
> > > sdma_engine *sdma)  static int sdma_alloc_bd(struct sdma_desc *desc)
> > > {
> > >  	u32 bd_size = desc->num_bd * sizeof(struct
> > > sdma_buffer_descriptor);
> > > +	struct sdma_engine *sdma = desc->sdmac->sdma;
> > >  	int ret = 0;
> > >
> > > -	desc->bd = dma_alloc_coherent(desc->sdmac->sdma->dev, bd_size,
> > > -				      &desc->bd_phys, GFP_NOWAIT);
> > > +	if (sdma->iram_pool)
> > > +		desc->bd = gen_pool_dma_alloc(sdma->iram_pool, bd_size,
> &desc->bd_phys);
> > > +	else
> > > +		desc->bd = dma_alloc_coherent(sdma->dev, bd_size,
> &desc->bd_phys,
> > > +GFP_NOWAIT);
> > > +
> > >  	if (!desc->bd) {
> > >  		ret = -ENOMEM;
> > >  		goto out;
> > > @@ -1394,9 +1407,12 @@ static int sdma_alloc_bd(struct sdma_desc
> > > *desc)  static void sdma_free_bd(struct sdma_desc *desc)  {
> > >  	u32 bd_size = desc->num_bd * sizeof(struct
> > > sdma_buffer_descriptor);
> > > +	struct sdma_engine *sdma = desc->sdmac->sdma;
> > >
> > > -	dma_free_coherent(desc->sdmac->sdma->dev, bd_size, desc->bd,
> > > -			  desc->bd_phys);
> > > +	if (sdma->iram_pool)
> > > +		gen_pool_free(sdma->iram_pool, (unsigned long)desc->bd,
> bd_size);
> > > +	else
> > > +		dma_free_coherent(desc->sdmac->sdma->dev, bd_size,
> desc->bd,
> > > +desc->bd_phys);
> > >  }
> > >
> > >  static void sdma_desc_free(struct virt_dma_desc *vd) @@ -2066,8
> > > +2082,8 @@ static int sdma_get_firmware(struct sdma_engine *sdma,
> > >
> > >  static int sdma_init(struct sdma_engine *sdma)  {
> > > +	int ccbsize;
> > >  	int i, ret;
> > > -	dma_addr_t ccb_phys;
> >
> > What is the motivation to put ccb_phys to struct sdma_engine? AFAICS
> > this is only used in sdma_init. Also the following patches of this
> > series are not using the struct member.
> 
> You are right. let me check other donwstream patches. If no one use it, it
> should be local variable.
Hi frank,
Yes, it should be local variable in current patch. I have checked downstream patches. We have optimized the sdma_init function in other patch, this patch need to put ccb_phys to struct sdma_engine.

BR
Joy Zou
> >
> > Best regards,
> > Alexander
> >
> > >
> > >  	ret = clk_enable(sdma->clk_ipg);
> > >  	if (ret)
> > > @@ -2083,10 +2099,15 @@ static int sdma_init(struct sdma_engine
> *sdma)
> > >  	/* Be sure SDMA has not started yet */
> > >  	writel_relaxed(0, sdma->regs + SDMA_H_C0PTR);
> > >
> > > -	sdma->channel_control = dma_alloc_coherent(sdma->dev,
> > > -			MAX_DMA_CHANNELS * sizeof(struct sdma_channel_control)
> +
> > > -			sizeof(struct sdma_context_data),
> > > -			&ccb_phys, GFP_KERNEL);
> > > +	ccbsize = MAX_DMA_CHANNELS * (sizeof(struct
> sdma_channel_control)
> > > +		  + sizeof(struct sdma_context_data));
> > > +
> > > +	if (sdma->iram_pool)
> > > +		sdma->channel_control =
> gen_pool_dma_alloc(sdma->iram_pool,
> > > +							   ccbsize, &sdma->ccb_phys);
> > > +	else
> > > +		sdma->channel_control = dma_alloc_coherent(sdma->dev,
> ccbsize, &sdma->ccb_phys,
> > > +							   GFP_KERNEL);
> > >
> > >  	if (!sdma->channel_control) {
> > >  		ret = -ENOMEM;
> > > @@ -2095,7 +2116,7 @@ static int sdma_init(struct sdma_engine
> *sdma)
> > >
> > >  	sdma->context = (void *)sdma->channel_control +
> > >  		MAX_DMA_CHANNELS * sizeof(struct sdma_channel_control);
> > > -	sdma->context_phys = ccb_phys +
> > > +	sdma->context_phys = sdma->ccb_phys +
> > >  		MAX_DMA_CHANNELS * sizeof(struct sdma_channel_control);
> > >
> > >  	/* disable all channels */
> > > @@ -2121,7 +2142,7 @@ static int sdma_init(struct sdma_engine
> *sdma)
> > >  	else
> > >  		writel_relaxed(0, sdma->regs + SDMA_H_CONFIG);
> > >
> > > -	writel_relaxed(ccb_phys, sdma->regs + SDMA_H_C0PTR);
> > > +	writel_relaxed(sdma->ccb_phys, sdma->regs + SDMA_H_C0PTR);
> > >
> > >  	/* Initializes channel's priorities */
> > >  	sdma_set_channel_priority(&sdma->channel[0], 7); @@ -2272,6
> > > +2293,12 @@ static int sdma_probe(struct platform_device *pdev)
> > >  			vchan_init(&sdmac->vc, &sdma->dma_device);
> > >  	}
> > >
> > > +	if (np) {
> > > +		sdma->iram_pool = of_gen_pool_get(np, "iram", 0);
> > > +		if (sdma->iram_pool)
> > > +			dev_info(&pdev->dev, "alloc bd from iram.\n");
> > > +	}
> > > +
> > >  	ret = sdma_init(sdma);
> > >  	if (ret)
> > >  		goto err_init;
> > >
> > >
> >
> >
> > --
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