linux-kernel - Re: [PATCH 4/5] mmc: mmci: stm32: define get_dctrl

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Date:   Wed, 6 Mar 2019 18:01:54 +0100
From:   Ludovic BARRE <ludovic.barre@...com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
CC:     Rob Herring <robh+dt@...nel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>
Subject: Re: [PATCH 4/5] mmc: mmci: stm32: define get_dctrl_cfg



On 3/6/19 2:31 PM, Ulf Hansson wrote:
> On Mon, 4 Mar 2019 at 11:17, Ludovic Barre <ludovic.Barre@...com> wrote:
>>
>> From: Ludovic Barre <ludovic.barre@...com>
>>
>> This patch defines get_dctrl_cfg callback for sdmmc variant.
>> sdmmc variant has specific stm32 transfer modes.
>> sdmmc data transfer mode selection could be:
>> -Block data transfer ending on block count.
>> -SDIO multibyte data transfer.
>> -MMC Stream data transfer (not used).
>> -Block data transfer ending with STOP_TRANSMISSION command.
>>
>> Signed-off-by: Ludovic Barre <ludovic.barre@...com>
>> ---
>>   drivers/mmc/host/mmci.h             |  5 +++++
>>   drivers/mmc/host/mmci_stm32_sdmmc.c | 21 +++++++++++++++++++++
>>   2 files changed, 26 insertions(+)
>>
>> diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
>> index 6f28f71..eb5d99af 100644
>> --- a/drivers/mmc/host/mmci.h
>> +++ b/drivers/mmc/host/mmci.h
>> @@ -131,6 +131,11 @@
>>   /* Control register extensions in the Qualcomm versions */
>>   #define MCI_DPSM_QCOM_DATA_PEND        BIT(17)
>>   #define MCI_DPSM_QCOM_RX_DATA_PEND BIT(20)
>> +/* Control register extensions in STM32 versions */
>> +#define MCI_DPSM_STM32_MODE_BLOCK      (0 << 2)
>> +#define MCI_DPSM_STM32_MODE_SDIO       (1 << 2)
>> +#define MCI_DPSM_STM32_MODE_STREAM     (2 << 2)
>> +#define MCI_DPSM_STM32_MODE_BLOCK_STOP (3 << 2)
>>
>>   #define MMCIDATACNT            0x030
>>   #define MMCISTATUS             0x034
>> diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
>> index cfbfc6f..e7bf744 100644
>> --- a/drivers/mmc/host/mmci_stm32_sdmmc.c
>> +++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
>> @@ -265,10 +265,31 @@ static void mmci_sdmmc_set_pwrreg(struct mmci_host *host, unsigned int pwr)
>>          }
>>   }
>>
>> +u32 sdmmc_get_dctrl_cfg(struct mmci_host *host)
>> +{
>> +       struct variant_data *variant = host->variant;
>> +       int blksz_bits;
>> +       u32 datactrl;
>> +
>> +       blksz_bits = ffs(host->data->blksz) - 1;
>> +       datactrl = variant->datactrl_dpsm_enable | blksz_bits << 4;
>> +
>> +       if (host->mmc->card && mmc_card_sdio(host->mmc->card) &&
>> +           host->data->blocks == 1)
> 
> These settings are not limited to deal with the block size bits.
> 
> Don't get me wrong, it seems reasonable to include them, but the
> generic code in mmci_start_data() also have code to cope with SDIO. I
> think we should start by splitting that up into a couple of
> helper/library functions, and make the legacy variant to use them.
> This should probably be done as a preparation to your series, so you
> can build on top of that.

I think you wish helper functions for each group of datactrl feature,
like for dpsm direction|sdio|ios timming. Each variant call theses 
helpers to define its own datactrl value. it's possible, no problem.

In mmci_start_data will remain the part on clk_reg for sdio card
	if (host->mmc->card && mmc_card_sdio(host->mmc->card)) {
		u32 clk;

		/*
		 * The ST Micro variant for SDIO small write transfers
		 * needs to have clock H/W flow control disabled,
		 * otherwise the transfer will not start. The threshold
		 * depends on the rate of MCLK.
		 */
		if (variant->st_sdio && data->flags & MMC_DATA_WRITE &&
		    (host->size < 8 ||
		     (host->size <= 8 && host->mclk > 50000000)))
			clk = host->clk_reg & ~variant->clkreg_enable;
		else
			clk = host->clk_reg | variant->clkreg_enable;

		mmci_write_clkreg(host, clk);
	}

it's OK ?

> 
> Does it make sense? If not, please tell and I can try to provide some
> patch to show you what I mean.
> 
> 
>> +               datactrl |= MCI_DPSM_STM32_MODE_SDIO;
>> +       else if (host->data->stop && !host->mrq->sbc)
>> +               datactrl |= MCI_DPSM_STM32_MODE_BLOCK_STOP;
>> +       else
>> +               datactrl |= MCI_DPSM_STM32_MODE_BLOCK;
>> +
>> +       return datactrl;
>> +}
>> +
>>   static struct mmci_host_ops sdmmc_variant_ops = {
>>          .validate_data = sdmmc_idma_validate_data,
>>          .prep_data = sdmmc_idma_prep_data,
>>          .unprep_data = sdmmc_idma_unprep_data,
>> +       .get_datactrl_cfg = sdmmc_get_dctrl_cfg,
>>          .dma_setup = sdmmc_idma_setup,
>>          .dma_start = sdmmc_idma_start,
>>          .dma_finalize = sdmmc_idma_finalize,
>> --
>> 2.7.4
>>
> 
> Kind regards
> Uffe
>