From: Andrew Gabbasov <andrew_gabbasov@mentor.com>
To: 'Geert Uytterhoeven' <geert@linux-m68k.org>
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
Date: Wed, 6 Oct 2021 21:11:51 +0300 [thread overview]
Message-ID: <000001d7badd$a8512d30$f8f38790$@mentor.com> (raw)
In-Reply-To: <CAMuHMdVVDpBAQR+H1TAnpf65aVbAL0Mm0km7Z9L7+1JuF6n1gQ@mail.gmail.com>
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
next prev parent reply other threads:[~2021-10-06 18:12 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-22 16:06 [PATCH] i2c: rcar: add SMBus block read support Andrew Gabbasov
2021-10-05 13:31 ` Geert Uytterhoeven
2021-10-06 18:11 ` Andrew Gabbasov [this message]
2021-10-06 18:23 ` [PATCH v2] " Andrew Gabbasov
2022-02-17 19:44 ` Wolfram Sang
2022-02-18 11:02 ` Gabbasov, Andrew
2022-03-15 10:45 ` Surachari, Bhuvanesh
2022-03-30 11:04 ` Wolfram Sang
2022-04-01 16:27 ` Wolfram Sang
2022-04-01 16:29 ` Wolfram Sang
2022-03-23 21:52 ` Eugeniu Rosca
2022-03-30 10:58 ` Wolfram Sang
2022-03-30 11:09 ` Wolfram Sang
2022-03-31 16:02 ` Eugeniu Rosca
2022-04-01 16:38 ` Wolfram Sang
2022-04-05 9:30 ` Eugeniu Rosca
2022-04-05 9:43 ` Wolfram Sang
2022-04-06 17:32 ` Eugeniu Rosca
2022-04-06 19:44 ` Wolfram Sang
2021-11-18 10:35 ` [PATCH] " Andrew Gabbasov
2022-01-09 19:20 ` Andrew Gabbasov
2022-01-25 6:45 ` Andrew Gabbasov
2022-02-17 14:40 ` Andrew Gabbasov
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