Messages in this thread | | | From | Brian Norris <> | Date | Tue, 23 Jan 2018 13:28:20 -0800 | Subject | Re: [PATCH v1 2/2] drm/bridge/synopsys: dsi: Add a warning msg on dsi read operations |
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Hi Philippe,
I see you sent this out already today, while I only just responded (late) to your questions about it... oh well :)
On Tue, Jan 23, 2018 at 6:26 AM, Philippe Cornu <philippe.cornu@st.com> wrote: > The DCS/GENERIC DSI read feature is not yet implemented so it > is important to warn the host_transfer() caller in case of > read operation requests. > > Signed-off-by: Philippe Cornu <philippe.cornu@st.com> > --- > drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c > index 096cf5e5bb30..e46ddff8601c 100644 > --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c > +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c > @@ -417,7 +417,14 @@ static ssize_t dw_mipi_dsi_host_transfer(struct mipi_dsi_host *host, > if (ret) > return ret; > > - nb_bytes = packet.size; > + if (msg->rx_buf && msg->rx_len > 0) {
It feels like you should do this check *before* you start writing anything. It's possible to have a combination TX/RX command, and it would be counterintuitive to only do half the operation then return with an argument error.
> + /* TODO dw drv improvements: implement read feature */ > + dev_warn(dsi->dev, "read operations not yet implemented\n"); > + return -EPERM;
I'm not sure -EPERM is right. Feels like -EINVAL, -ENOSYS, or -EOPNOTSUPP. I think -ENOSYS actually has been abused somewhat, so maybe one of the other two.
> +
Spurious blank line?
> + } else { > + nb_bytes = packet.size; > + }
You don't actually need to put this sort of thing in the 'else' case. The other branch is an error-handling case, which definitely 'return's early, and it's pretty standard coding style to avoid indenting the "good" path like this.
Brian
> > return nb_bytes; > } > -- > 2.15.1 >
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