linux-kernel - Re: [PATCH] mmc: core: Add support for the eMMC RTC feature in mmc

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Message-ID: <20211207052647.GA5700@nishad>
Date:   Tue, 7 Dec 2021 10:56:48 +0530
From:   Nishad Kamdar <nishadkamdar@...il.com>
To:     Stephen Boyd <swboyd@...omium.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Jens Axboe <axboe@...nel.dk>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Bean Huo <beanhuo@...ron.com>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Avri Altman <avri.altman@....com>,
        Huijin Park <huijin.park@...sung.com>,
        Yue Hu <huyue2@...ong.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mmc: core: Add support for the eMMC RTC feature in
 mmc_ops

On Mon, Dec 06, 2021 at 12:44:14PM -0800, Stephen Boyd wrote:
> Quoting Nishad Kamdar (2021-12-05 11:10:08)
> > diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
> > index d63d1c735335..490372341b3b 100644
> > --- a/drivers/mmc/core/mmc_ops.c
> > +++ b/drivers/mmc/core/mmc_ops.c
> > @@ -1063,3 +1063,62 @@ int mmc_sanitize(struct mmc_card *card, unsigned int timeout_ms)
> >         return err;
> >  }
> >  EXPORT_SYMBOL_GPL(mmc_sanitize);
> > +
> > +int mmc_set_time(struct mmc_card *card, struct mmc_host *host,
> > +                u8 rtc_info_type, u64 seconds)
> > +{
> > +       struct mmc_request mrq = {};
> > +       struct mmc_command cmd = {};
> > +       struct mmc_data data = {};
> > +       struct scatterlist sg;
> > +       int err = 0;
> > +       u8 *data_buf;
> > +
> > +       data_buf = kzalloc(512, GFP_KERNEL);
> 
> Use some #define for 512 because it's used three times in here?
ok, but there is not #define for 512 as it is the variable block size
value. Hence, other functions in the same file like mmc_get_ext_csd() also use
the 512 value directly.

> > +       if (!data_buf)
> > +               return -ENOMEM;
> > +
> > +       if (rtc_info_type == 0x01 || rtc_info_type == 0x02 ||
> > +           rtc_info_type == 0x03) {
> > +               data_buf[0] = 0x01;
> > +               data_buf[1] = rtc_info_type;
> > +               memcpy(&data_buf[2], &seconds, sizeof(u64));
> 
> Use sizeof(seconds) instead?
> 
ok, I will do that.

> > +       } else {
> > +               pr_err("%s: invalid rtc_info_type %d\n",
> > +                      mmc_hostname(host), rtc_info_type);
> > +               kfree(data_buf);
> > +               return -EINVAL;
> > +       }
> > +
> > +       mrq.cmd = &cmd;
> > +       mrq.data = &data;
> > +
> > +       cmd.opcode = MMC_SET_TIME;
> > +       cmd.arg = 0;
> > +       cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
> > +
> > +       data.blksz = 512;
> > +       data.blocks = 1;
> > +       data.flags = MMC_DATA_WRITE;
> > +       data.sg = &sg;
> > +       data.sg_len = 1;
> > +       sg_init_one(&sg, data_buf, 512);
> > +
> > +       mmc_set_data_timeout(&data, card);
> > +
> > +       mmc_wait_for_req(host, &mrq);
> > +
> > +       if (cmd.error) {
> > +               err = cmd.error;
> > +               goto out;
> > +       }
> > +
> > +       if (data.error) {
> > +               err = data.error;
> > +               goto out;
> > +       }
> 
> Why not
> 
> 	if (cmd.error) {
> 		err = cmd.error;
> 	} else if (data.error) {
> 		err = data.error;
> 	} else {
> 		err = 0;
> 	}
> 
> > +out:
> 
> And then drop out: and the assignment of err to 0 up above?
ok, I will do that.

> 
> > +       kfree(data_buf);
> > +       return err;
> > +}
> > +EXPORT_SYMBOL_GPL(mmc_set_time);