Linux SPI subsystem development
 help / color / mirror / Atom feed
From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Raju Rangoju <Raju.Rangoju@amd.com>
Cc: <broonie@kernel.org>,  <linux-spi@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	 Krishnamoorthi M <krishnamoorthi.m@amd.com>,
	 Akshata MukundShetty <akshata.mukundshetty@amd.com>
Subject: Re: [PATCH] spi: spi-mem: Add fix to avoid divide error
Date: Thu, 24 Apr 2025 16:25:21 +0200	[thread overview]
Message-ID: <87msc5hc1a.fsf@bootlin.com> (raw)
In-Reply-To: <20250424121333.417372-1-Raju.Rangoju@amd.com> (Raju Rangoju's message of "Thu, 24 Apr 2025 17:43:33 +0530")


> --- a/drivers/spi/spi-mem.c
> +++ b/drivers/spi/spi-mem.c
> @@ -596,7 +596,11 @@ u64 spi_mem_calc_op_duration(struct spi_mem_op *op)
>  	ns_per_cycles = 1000000000 / op->max_freq;
>  	ncycles += ((op->cmd.nbytes * 8) / op->cmd.buswidth) / (op->cmd.dtr ? 2 : 1);
>  	ncycles += ((op->addr.nbytes * 8) / op->addr.buswidth) / (op->addr.dtr ? 2 : 1);
> -	ncycles += ((op->dummy.nbytes * 8) / op->dummy.buswidth) / (op->dummy.dtr ? 2 : 1);
> +
> +	/* Dummy bytes are optional for some SPI flash memory operations */
> +	if (op->dummy.nbytes)
> +		ncycles += ((op->dummy.nbytes * 8) / op->dummy.buswidth) / (op->dummy.dtr ? 2 : 1);
> +
>  	ncycles += ((op->data.nbytes * 8) / op->data.buswidth) / (op->data.dtr ? 2 : 1);
>  
>  	return ncycles * ns_per_cycles;

Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>

Actually even address bytes sometimes may be skipped (eg. status reads). But there is no
reason for using spi_mem_calc_op_duration() in this case.

Thanks,
Miquèl

  parent reply	other threads:[~2025-04-24 14:25 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-24 12:13 [PATCH] spi: spi-mem: Add fix to avoid divide error Raju Rangoju
2025-04-24 12:15 ` Mark Brown
2025-04-24 12:27   ` Rangoju, Raju
2025-04-24 12:44     ` Mark Brown
2025-04-24 14:25 ` Miquel Raynal [this message]
2025-04-25 16:03 ` Mark Brown
2025-06-02  9:45 ` Dan Carpenter
2025-06-09 10:40   ` Rangoju, Raju
2025-06-10  8:03     ` Dan Carpenter

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87msc5hc1a.fsf@bootlin.com \
    --to=miquel.raynal@bootlin.com \
    --cc=Raju.Rangoju@amd.com \
    --cc=akshata.mukundshetty@amd.com \
    --cc=broonie@kernel.org \
    --cc=krishnamoorthi.m@amd.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-spi@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox