On Wed, 22 Jun 2022, William Tseng <william.tseng@xxxxxxxxx> wrote:
> To support Host to read data from Peripheral after
> a DCS read command is sent over DSI.
Please find a couple of comments inline below. Basically with them fixed
this is
Acked-by: Jani Nikula <jani.nikula@xxxxxxxxx>
I'm afraid I just don't have the time for further detailed review right
now. I do note that this has no regression potential for the existing
DSI write paths, so (apart from the potential buffer overflow I note
below) this should be a pretty safe change, as long as it's tested to
work.
BR,
Jani.
>
> v1: initial version.
> v2:
> - adding error message when failing to place BTA.
> - returning byte number instead of 0 for the read
> function dsi_read_pkt_payld().
> v3: fixing coding style warning.
> v4:
> - correcting the data type of returning data for
> the read function dsi_read_pkt_payld().
> v5: adding change history as part of commit messages.
> v6: according to the review comments from Jani,
> - drop the commented out variable "hdr_data".
> - use int insteaf of u8 as the data type of the loop
> variable i.
> - use intel_de_rmw() for read-modify-write.
> - add new function place_bta_request() to keep
> payload receive function clean.
> - explicitly clear the READ_UNLOADS_DW bit of
> DSI_CMD_RXCTL before reading receive payload.
> - use two loops to copy received data.
> - remove the unrelated change from this patch,
> which is made to gen11_dsi_setup_timeouts().
> - drop the comment in gen11_dsi_host_transfer().
> - change the condition to call the payload
> receive function in gen11_dsi_host_transfer().
>
> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Vandita Kulkarni <vandita.kulkarni@xxxxxxxxx>
> Cc: Lee Shawn C <shawn.c.lee@xxxxxxxxx>
> Signed-off-by: William Tseng <william.tseng@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/icl_dsi.c | 76 ++++++++++++++++++++-
> drivers/gpu/drm/i915/display/icl_dsi_regs.h | 13 ++++
> 2 files changed, 86 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c
> index 19bf717fd4cb..edf20016af91 100644
> --- a/drivers/gpu/drm/i915/display/icl_dsi.c
> +++ b/drivers/gpu/drm/i915/display/icl_dsi.c
> @@ -201,6 +201,75 @@ static int dsi_send_pkt_hdr(struct intel_dsi_host *host,
> return 0;
> }
>
> +static bool place_bta_request(struct intel_dsi_host *host)
> +{
> + struct intel_dsi *intel_dsi = host->intel_dsi;
> + struct drm_i915_private *dev_priv = to_i915(intel_dsi->base.base.dev);
> + enum transcoder dsi_trans = dsi_port_to_transcoder(host->port);
> +
> + /* step2a(i): specify Turn-Around timeout */
> + intel_de_rmw(dev_priv, DSI_TA_TO(dsi_trans), TA_TIMEOUT_VALUE_MASK,
> + TA_TIMEOUT_VALUE(intel_dsi->turn_arnd_val));
> +
> + /* step2a(ii): specify maximum allowed time */
> + intel_de_rmw(dev_priv, DSI_LPRX_HOST_TO(dsi_trans), ~LPRX_TIMEOUT_VALUE_MASK,
> + LPRX_TIMEOUT_VALUE(intel_dsi->lp_rx_timeout));
> +
> + /* check if header credit available */
> + if (!wait_for_header_credits(dev_priv, dsi_trans, 1)) {
> + drm_err(&dev_priv->drm, "not ready to recive payload\n");
> + return false;
> + }
> +
> + /* place BTA request */
> + intel_de_rmw(dev_priv, DSI_LP_MSG(dsi_trans), LINK_BTA, LINK_BTA);
> +
> + return true;
> +}
> +
> +static int dsi_read_pkt_payld(struct intel_dsi_host *host,
> + u8 *rx_buf, size_t rx_len)
> +{
> + struct intel_dsi *intel_dsi = host->intel_dsi;
> + struct drm_i915_private *dev_priv = to_i915(intel_dsi->base.base.dev);
> + enum transcoder dsi_trans = dsi_port_to_transcoder(host->port);
> + u32 tmp, payld_data;
> + u32 payld_dw;
> + int i, j;
> +
> + if (rx_len <= 0)
> + return 0;
> +
> + /* do not unload receive queue */
> + tmp = intel_de_read(dev_priv, DSI_CMD_RXCTL(dsi_trans));
> + tmp &= ~READ_UNLOADS_DW;
> + intel_de_write(dev_priv, DSI_CMD_RXCTL(dsi_trans), tmp);
> +
> + /* step2: place a BTA request */
> + if (!place_bta_request(host))
> + return -EBUSY;
> +
> + /* step4a: wait and read payload */
> + if (wait_for_us(((intel_de_read(dev_priv, DSI_CMD_RXCTL(dsi_trans)) &
> + NUMBER_RX_PLOAD_DW_MASK) >> NUMBER_RX_PLOAD_DW_SHIFT) > 0, 100000)) {
> + drm_err(&dev_priv->drm, "DSI fails to receive payload\n");
> + return -EBUSY;
> + }
> +
> + tmp = intel_de_read(dev_priv, DSI_CMD_RXCTL(dsi_trans));
> + payld_dw = (tmp & NUMBER_RX_PLOAD_DW_MASK) >> NUMBER_RX_PLOAD_DW_SHIFT;
> +
> + for (i = 0; i < payld_dw; i++) {
> +
> + payld_data = intel_de_read(dev_priv, DSI_CMD_RXPYLD(dsi_trans));
> +
> + for (j = 0; j < min_t(u32, rx_len - (i * 4), 4); j++)
> + *(rx_buf + (i * 4 + j)) = (payld_data >> 8 * j) & 0xff;
Mmh, no matter what the hardware returns, you can't overflow rx_len in
rx_buf.
> + }
> +
> + return ((i - 1) * 4 + j);
> +}
> +
> void icl_dsi_frame_update(struct intel_crtc_state *crtc_state)
> {
> struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> @@ -1837,9 +1906,10 @@ static ssize_t gen11_dsi_host_transfer(struct mipi_dsi_host *host,
> if (ret < 0)
> return ret;
>
> - //TODO: add payload receive code if needed
> -
> - ret = sizeof(dsi_pkt.header) + dsi_pkt.payload_length;
> + if (msg->rx_buf)
Matter of taste, I'd check for msg->rx_len here, and the return an error
from dsi_read_pkt_payld() if !msg->rx_buf.
> + ret = dsi_read_pkt_payld(intel_dsi_host, msg->rx_buf, msg->rx_len);
> + else
> + ret = sizeof(dsi_pkt.header) + dsi_pkt.payload_length;
>
> return ret;
> }
> diff --git a/drivers/gpu/drm/i915/display/icl_dsi_regs.h b/drivers/gpu/drm/i915/display/icl_dsi_regs.h
> index f78f28b8dd94..a77a49b42d60 100644
> --- a/drivers/gpu/drm/i915/display/icl_dsi_regs.h
> +++ b/drivers/gpu/drm/i915/display/icl_dsi_regs.h
> @@ -251,6 +251,18 @@
> #define NUMBER_RX_PLOAD_DW_MASK (0xff << 0)
> #define NUMBER_RX_PLOAD_DW_SHIFT 0
>
> +#define _DSI_CMD_RXHDR_0 0x6b0e0
> +#define _DSI_CMD_RXHDR_1 0x6b8e0
> +#define DSI_CMD_RXHDR(tc) _MMIO_DSI(tc, \
> + _DSI_CMD_RXHDR_0,\
> + _DSI_CMD_RXHDR_1)
> +
> +#define _DSI_CMD_RXPYLD_0 0x6b0e4
> +#define _DSI_CMD_RXPYLD_1 0x6b8e4
> +#define DSI_CMD_RXPYLD(tc) _MMIO_DSI(tc, \
> + _DSI_CMD_RXPYLD_0,\
> + _DSI_CMD_RXPYLD_1)
> +
> #define _DSI_CMD_TXCTL_0 0x6b0d0
> #define _DSI_CMD_TXCTL_1 0x6b8d0
> #define DSI_CMD_TXCTL(tc) _MMIO_DSI(tc, \
> @@ -294,6 +306,7 @@
> #define LPTX_IN_PROGRESS (1 << 17)
> #define LINK_IN_ULPS (1 << 16)
> #define LINK_ULPS_TYPE_LP11 (1 << 8)
> +#define LINK_BTA (1 << 1)
> #define LINK_ENTER_ULPS (1 << 0)
>
> /* DSI timeout registers */
--
Jani Nikula, Intel Open Source Graphics Center
