Messages in this thread | | | From | Andrew Gabbasov <> | Subject | RE: [PATCH] i2c: rcar: add SMBus block read support | Date | Wed, 6 Oct 2021 21:11:51 +0300 |
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Hi Geert,
Thank you for your review!
> -----Original Message----- > From: Geert Uytterhoeven <geert@linux-m68k.org> > Sent: Tuesday, October 05, 2021 4:32 PM > To: Gabbasov, Andrew <Andrew_Gabbasov@mentor.com> > Cc: Linux-Renesas <linux-renesas-soc@vger.kernel.org>; Linux I2C <linux-i2c@vger.kernel.org>; Linux Kernel > Mailing List <linux-kernel@vger.kernel.org>; Wolfram Sang <wsa+renesas@sang-engineering.com>; Surachari, > Bhuvanesh <Bhuvanesh_Surachari@mentor.com> > Subject: Re: [PATCH] i2c: rcar: add SMBus block read support > > Hi Andrew, > > On Wed, Sep 22, 2021 at 6:14 PM Andrew Gabbasov > <andrew_gabbasov@mentor.com> wrote: > > The smbus block read is not currently supported for rcar i2c devices. > > This patchset adds the support to rcar i2c bus so that blocks of data > > can be read using SMbus block reads.(using i2c_smbus_read_block_data() > > function from the i2c-core-smbus.c). > > > > Inspired by commit 8e8782c71595 ("i2c: imx: add SMBus block read support") > > > > This patch (adapted) was tested with v4.14, but due to lack of real > > hardware with SMBus block read operations support, using "simulation", > > that is manual analysis of data, read from plain I2C devices with > > SMBus block read request. > > > > Signed-off-by: Bhuvanesh Surachari <bhuvanesh_surachari@mentor.com> > > Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com> > > Thanks for your patch! > > > --- a/drivers/i2c/busses/i2c-rcar.c > > +++ b/drivers/i2c/busses/i2c-rcar.c > > @@ -429,9 +431,16 @@ static bool rcar_i2c_dma(struct rcar_i2c_priv *priv) > > /* > > * The last two bytes needs to be fetched using PIO in > > * order for the STOP phase to work. > > + * > > + * For SMBus block read the first byte was received using PIO. > > So it might be easier to read, and more maintainable, to keep the > old assignments: > > buf = priv->msg->buf; > len = priv->msg->len - 2; > > and adjust them for SMBus afterwards: > > if (block_data) { > /* For SMBus block read the first byte was received using PIO */ > buf++; > len--; > } > > ? > > > */ > > - buf = priv->msg->buf; > > - len = priv->msg->len - 2; > > + if (block_data) { > > + buf = priv->msg->buf + 1; > > + len = priv->msg->len - 3; > > + } else { > > + buf = priv->msg->buf; > > + len = priv->msg->len - 2; > > + } > > } else { > > /* > > * First byte in message was sent using PIO. > > And below we have another case handling buf and len :-( > > So perhaps: > > buf = priv->msg->buf; > len = priv->msg->len; > > if (read) { > /* > * The last two bytes needs to be fetched using PIO in > * order for the STOP phase to work. > */ > len -= 2; > } > if (!read || block_data) { > /* First byte in message was sent using PIO * > buf++; > len--; > }
Probably I was trying to minimize the changes ;-)
However, I agree with you that the whole code fragment can be simplified and your variant indeed looks more clean and understandable. Thank you for your suggestion, I'll submit version 2 of the patch with this fragment changed.
Thanks!
Best regards, Andrew
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