netdev - Re: [PATCH net-next v6 02/13] net: wwan: t7xx: Add control DMA interface

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Date:   Thu, 21 Apr 2022 14:55:58 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Ricardo Martinez <ricardo.martinez@...ux.intel.com>
cc:     Netdev <netdev@...r.kernel.org>, linux-wireless@...r.kernel.org,
        kuba@...nel.org, davem@...emloft.net, johannes@...solutions.net,
        ryazanov.s.a@...il.com, loic.poulain@...aro.org,
        m.chetan.kumar@...el.com, chandrashekar.devegowda@...el.com,
        linuxwwan@...el.com, chiranjeevi.rapolu@...ux.intel.com,
        haijun.liu@...iatek.com, amir.hanania@...el.com,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        dinesh.sharma@...el.com, eliot.lee@...el.com,
        moises.veleta@...el.com, pierre-louis.bossart@...el.com,
        muralidharan.sethuraman@...el.com, Soumya.Prakash.Mishra@...el.com,
        sreehari.kancharla@...el.com, madhusmita.sahu@...el.com
Subject: Re: [PATCH net-next v6 02/13] net: wwan: t7xx: Add control DMA
 interface

On Thu, 7 Apr 2022, Ricardo Martinez wrote:

> From: Haijun Liu <haijun.liu@...iatek.com>
> 
> Cross Layer DMA (CLDMA) Hardware interface (HIF) enables the control
> path of Host-Modem data transfers. CLDMA HIF layer provides a common
> interface to the Port Layer.
> 
> CLDMA manages 8 independent RX/TX physical channels with data flow
> control in HW queues. CLDMA uses ring buffers of General Packet
> Descriptors (GPD) for TX/RX. GPDs can represent multiple or single
> data buffers (DB).
> 
> CLDMA HIF initializes GPD rings, registers ISR handlers for CLDMA
> interrupts, and initializes CLDMA HW registers.
> 
> CLDMA TX flow:
> 1. Port Layer write
> 2. Get DB address
> 3. Configure GPD
> 4. Triggering processing via HW register write
> 
> CLDMA RX flow:
> 1. CLDMA HW sends a RX "done" to host
> 2. Driver starts thread to safely read GPD
> 3. DB is sent to Port layer
> 4. Create a new buffer for GPD ring
> 
> Note: This patch does not enable compilation since it has dependencies
> such as t7xx_pcie_mac_clear_int()/t7xx_pcie_mac_set_int() and
> struct t7xx_pci_dev which are added by the core patch.
> 
> Signed-off-by: Haijun Liu <haijun.liu@...iatek.com>
> Signed-off-by: Chandrashekar Devegowda <chandrashekar.devegowda@...el.com>
> Co-developed-by: Ricardo Martinez <ricardo.martinez@...ux.intel.com>
> Signed-off-by: Ricardo Martinez <ricardo.martinez@...ux.intel.com>
> 
> >From a WWAN framework perspective:
> Reviewed-by: Loic Poulain <loic.poulain@...aro.org>
> 
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>

> +struct cldma_tgpd {
> +	u8 gpd_flags;
> +	u8 not_used1;
> +	u8 not_used2;
> +	u8 debug_id;
> +	__le32 next_gpd_ptr_h;
> +	__le32 next_gpd_ptr_l;
> +	__le32 data_buff_bd_ptr_h;
> +	__le32 data_buff_bd_ptr_l;
> +	__le16 data_buff_len;
> +	__le16 not_used3;
> +};
> +
> +struct cldma_rgpd {
> +	u8 gpd_flags;
> +	u8 not_used1;
> +	__le16 data_allow_len;
> +	__le32 next_gpd_ptr_h;
> +	__le32 next_gpd_ptr_l;
> +	__le32 data_buff_bd_ptr_h;
> +	__le32 data_buff_bd_ptr_l;
> +	__le16 data_buff_len;
> +	u8 not_used2;
> +	u8 debug_id;
> +};

A small additional thing...

If you put next_gpd_ptr_h, next_gpd_ptr_l, data_buff_bd_ptr_h, and 
data_buff_bd_ptr_l into another struct inside these structs, 
t7xx_cldma_tgpd_set_data_ptr() and friends don't require duplicated 
versions for tgpd and rgpd.

-- 
 i.