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Message-ID: <e09b50b8-dd65-4636-aa35-42efc86bba16@quicinc.com>
Date: Sat, 1 Feb 2025 23:24:50 +0530
From: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
To: Frank Li <Frank.Li@....com>,
Alexandre Belloni
<alexandre.belloni@...tlin.com>,
Miquel Raynal <miquel.raynal@...tlin.com>,
Conor Culhane <conor.culhane@...vaco.com>
CC: <linux-i3c@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
<imx@...ts.linux.dev>
Subject: Re: [PATCH 1/2] i3c: Add basic HDR support
Hi Frank,
On 1/30/2025 1:35 AM, Frank Li wrote:
> I3C HDR requires enter/exit patterns during each I3C transfer. Add a new
> API i3c_device_do_priv_xfers_mode(). The existing
> i3c_device_do_priv_xfers() now calls i3c_device_do_priv_xfers_mode(I3C_SDR)
> to maintain backward compatibility.
>
> Introduce a 'cmd' field in 'struct i3c_priv_xfer', using an anonymous union
> with 'rnw' since HDR mode relies on read/write commands instead of the
> 'rnw' bit in the address as in SDR mode.
>
> Add a priv_xfers_mode callback for I3C master drivers. If priv_xfers_mode
> is not implemented, fallback to SDR mode using the existing priv_xfers
> callback.
>
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
> Why not add hdr mode in struct i3c_priv_xfer because mode can't be mixed in
> one i3c transfer. for example, can't send a HDR follow one SDR between
> START and STOP.
>
Is it wise to add two function inside main funcion and separate SDR vs
HDR ? so we don't need to change current function arguments.
> i3c_priv_xfer should be treat as whole i3c transactions. If user want send
> HDR follow SDR, should be call i3c_device_do_priv_xfers_mode() twice,
> instead put into a big i3c_priv_xfer[n].
> ---
> drivers/i3c/device.c | 19 +++++++++++++------
> drivers/i3c/internals.h | 2 +-
> drivers/i3c/master.c | 8 +++++++-
> include/linux/i3c/device.h | 12 +++++++++++-
> include/linux/i3c/master.h | 3 +++
> 5 files changed, 35 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/i3c/device.c b/drivers/i3c/device.c
> index e80e487569146..e3db3a6a9e4f6 100644
> --- a/drivers/i3c/device.c
> +++ b/drivers/i3c/device.c
> @@ -15,12 +15,13 @@
> #include "internals.h"
>
> /**
> - * i3c_device_do_priv_xfers() - do I3C SDR private transfers directed to a
> - * specific device
> + * i3c_device_do_priv_xfers_mode() - do I3C SDR private transfers directed to a
> + * specific device
> *
> * @dev: device with which the transfers should be done
> * @xfers: array of transfers
> * @nxfers: number of transfers
> + * @mode: transfer mode
> *
> * Initiate one or several private SDR transfers with @dev.
> *
> @@ -32,9 +33,9 @@
> * driver needs to resend the 'xfers' some time later.
> * See I3C spec ver 1.1.1 09-Jun-2021. Section: 5.1.2.2.3.
> */
> -int i3c_device_do_priv_xfers(struct i3c_device *dev,
> - struct i3c_priv_xfer *xfers,
> - int nxfers)
> +int i3c_device_do_priv_xfers_mode(struct i3c_device *dev,
> + struct i3c_priv_xfer *xfers,
> + int nxfers, enum i3c_hdr_mode mode)
why can't we pass mode as another structure member inside struct
i3c_priv_xfer ? Adding function agrument parameter impacts existing drivers.
> {
> int ret, i;
>
> @@ -47,11 +48,17 @@ int i3c_device_do_priv_xfers(struct i3c_device *dev,
> }
>
> i3c_bus_normaluse_lock(dev->bus);
> - ret = i3c_dev_do_priv_xfers_locked(dev->desc, xfers, nxfers);
> + ret = i3c_dev_do_priv_xfers_locked(dev->desc, xfers, nxfers, mode);
> i3c_bus_normaluse_unlock(dev->bus);
>
> return ret;
> }
> +EXPORT_SYMBOL_GPL(i3c_device_do_priv_xfers_mode);
> +
> +int i3c_device_do_priv_xfers(struct i3c_device *dev, struct i3c_priv_xfer *xfers, int nxfers)
> +{
> + return i3c_device_do_priv_xfers_mode(dev, xfers, nxfers, I3C_SDR);
> +}
> EXPORT_SYMBOL_GPL(i3c_device_do_priv_xfers);
>
> /**
> diff --git a/drivers/i3c/internals.h b/drivers/i3c/internals.h
> index 433f6088b7cec..553edc9846ac0 100644
> --- a/drivers/i3c/internals.h
> +++ b/drivers/i3c/internals.h
> @@ -16,7 +16,7 @@ void i3c_bus_normaluse_unlock(struct i3c_bus *bus);
> int i3c_dev_setdasa_locked(struct i3c_dev_desc *dev);
> int i3c_dev_do_priv_xfers_locked(struct i3c_dev_desc *dev,
> struct i3c_priv_xfer *xfers,
> - int nxfers);
> + int nxfers, enum i3c_hdr_mode mode);
> int i3c_dev_disable_ibi_locked(struct i3c_dev_desc *dev);
> int i3c_dev_enable_ibi_locked(struct i3c_dev_desc *dev);
> int i3c_dev_request_ibi_locked(struct i3c_dev_desc *dev,
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index d5dc4180afbcf..67aaba0a38db2 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -2945,7 +2945,7 @@ int i3c_dev_setdasa_locked(struct i3c_dev_desc *dev)
>
> int i3c_dev_do_priv_xfers_locked(struct i3c_dev_desc *dev,
> struct i3c_priv_xfer *xfers,
> - int nxfers)
> + int nxfers, enum i3c_hdr_mode mode)
> {
> struct i3c_master_controller *master;
>
> @@ -2956,9 +2956,15 @@ int i3c_dev_do_priv_xfers_locked(struct i3c_dev_desc *dev,
> if (!master || !xfers)
> return -EINVAL;
>
> + if (master->ops->priv_xfers_mode)
> + return master->ops->priv_xfers_mode(dev, xfers, nxfers, mode);
> +
> if (!master->ops->priv_xfers)
> return -ENOTSUPP;
>
> + if (mode != I3C_SDR)
> + return -EINVAL;
> +
> return master->ops->priv_xfers(dev, xfers, nxfers);
> }
>
> diff --git a/include/linux/i3c/device.h b/include/linux/i3c/device.h
> index b674f64d0822e..7ce70d0967e27 100644
> --- a/include/linux/i3c/device.h
> +++ b/include/linux/i3c/device.h
> @@ -40,11 +40,13 @@ enum i3c_error_code {
>
> /**
> * enum i3c_hdr_mode - HDR mode ids
> + * @I3C_SDR: SDR mode (NOT HDR mode)
> * @I3C_HDR_DDR: DDR mode
> * @I3C_HDR_TSP: TSP mode
> * @I3C_HDR_TSL: TSL mode
> */
> enum i3c_hdr_mode {
> + I3C_SDR,
> I3C_HDR_DDR,
> I3C_HDR_TSP,
> I3C_HDR_TSL,
> @@ -53,6 +55,7 @@ enum i3c_hdr_mode {
> /**
> * struct i3c_priv_xfer - I3C SDR private transfer
> * @rnw: encodes the transfer direction. true for a read, false for a write
> + * @cmd: Read/Write command in HDR mode, read: 0x80 - 0xff, write: 0x00 - 0x7f
> * @len: transfer length in bytes of the transfer
> * @actual_len: actual length in bytes are transferred by the controller
> * @data: input/output buffer
> @@ -61,7 +64,10 @@ enum i3c_hdr_mode {
> * @err: I3C error code
> */
> struct i3c_priv_xfer {
> - u8 rnw;
> + union {
> + u8 rnw;
> + u8 cmd;
> + };
> u16 len;
> u16 actual_len;
> union {
> @@ -301,6 +307,10 @@ int i3c_device_do_priv_xfers(struct i3c_device *dev,
> struct i3c_priv_xfer *xfers,
> int nxfers);
>
> +int i3c_device_do_priv_xfers_mode(struct i3c_device *dev,
> + struct i3c_priv_xfer *xfers,
> + int nxfers, enum i3c_hdr_mode mode);
> +
> int i3c_device_do_setdasa(struct i3c_device *dev);
>
> void i3c_device_get_info(const struct i3c_device *dev, struct i3c_device_info *info);
> diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
> index 12d532b012c5a..352bd41139569 100644
> --- a/include/linux/i3c/master.h
> +++ b/include/linux/i3c/master.h
> @@ -472,6 +472,9 @@ struct i3c_master_controller_ops {
> int (*priv_xfers)(struct i3c_dev_desc *dev,
> struct i3c_priv_xfer *xfers,
> int nxfers);
> + int (*priv_xfers_mode)(struct i3c_dev_desc *dev,
> + struct i3c_priv_xfer *xfers,
> + int nxfers, enum i3c_hdr_mode mode);
> int (*attach_i2c_dev)(struct i2c_dev_desc *dev);
> void (*detach_i2c_dev)(struct i2c_dev_desc *dev);
> int (*i2c_xfers)(struct i2c_dev_desc *dev,
>
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